Answer:
C.
Step-by-step explanation:
When you replace x by x - h, the graph is shifted h units horizontally.
Here, x is replaced by x - 6.
x - h = x - 6
h = 6
6 is positive, so the shift is 6 units to the right.
Answer: C.
This rectangular wall is to be painted. Paint is sold in tins. How much does it cost to paint the wall?
Answer:
£23.96
Step-by-step explanation:
Area to be painted:
3.6 m * 8.3 m = 29.88 m^2
The area to be painted is 29.88 m^2.
A tin of paint covers 8 m^2. We divide to find the number of tins needed.
29.88/8 = 3.735
Since full tins must be bought, the smallest number of tins needed is 4.
Now we find the price of 4 tins. 1 tin costs £5.99, so 4 tins cost:
4 * £5.99 = £23.96
what is the answer to 1/8=s-3/4
Answer:
7/8 =s
Step-by-step explanation:
1/8=s-3/4
Add 3/4
1/8 + 3/4 = s -3/4 +3/4
1/8 + 3/4 = s
Get a common denominator
1/8 + 3/4 *2/2 = s
1/8 + 6/8 =s
7/8 =s
1/8 = s - 3/4
1/8 = s -6/8 ( * 2/2)
7/8 = s
s = 7/8
A bag contains twelve marbles, which includes seven red marbles and five blue marbles. Roja reaches into the bag and pulls out four marbles. a) How many different sets of four marbles can be pulled from this bag? b) How many of these sets contain two red marbles and two blue marbles? c) How many of these sets contain all red marbles? d) How many of these sets contain all red marbles or all blue marbles?
Answer:
a) 495
b) 210
c) 35
d) 40
Step-by-step explanation:
Given a total of 12 marbles.
n = 12
Number of red marbles = 7
Number of blue marbles = 5
a) Number of different sets of 4 marbles that can be made from this bag ?
This is a simple combination problem.
where n = 12 and r = 4.
So, answer will be:
[tex]_{12}C_4[/tex]
Formula:
[tex]_{n}C_r = \dfrac{n!}{(n-r)!r!}[/tex]
[tex]_{12}C_4 = \dfrac{12!}{(8)!4!} = \dfrac{12\times 11\times 10\times 9}{4 \times 3\times 2} =\bold{495}[/tex]
b) Two red and two blue marbles:
The answer will be:
[tex]_{7}C_2 \times _{5}C_2 = \dfrac{7\times 6}{2} \times \dfrac{5\times 4}{2} =\bold{210}[/tex]
c) all red marbles.(4 chosen out of 7 red and 0 chosen out of 5 blue marbles)
[tex]_{7}C_4 \times _{5}C_0 = \dfrac{7\times 6\times 5\times 4}{4\times 3\times 2} =\bold{35}[/tex]
d) all red or all blue.(all red marbles plus all blue marbles)
All red marbles:
[tex]_{7}C_4 \times _{5}C_0 = \dfrac{7\times 6\times 5\times 4}{4\times 3\times 2} \times 1=\bold{35}[/tex]
All blue marbles:
[tex]_{7}C_0 \times _{5}C_4 = 1 \times \dfrac{5\times 4\times 3\times 2}{4\times 3\times 2} =\bold{5}[/tex]
So, answer is 40.
If 4SINB=3SIN(2A+B) :
Prove that:7COT(A+B)=COTA
Answer:
Step-by-step explanation:
Given the expression 4sinB = 3sin(2A+B), we are to show that the expression 7cot(A+B) = cotA
Starting with the expression
4sinB= 3sin(2A+B)
Let us re write angle B = (A + B) - A
and 2A + B = (A + B) + A
Substituting the derived expression back into the original expression ww will have;
4Sin{(A + B) - A } = 3Sin{(A + B)+ A}
From trigonometry identity;
Sin(D+E) = SinDcosE + CosDSinE
Sin(D-E) = SinDcosE - CosDSinE
Applying this in the expression above;
4{Sin(A+B)CosA - Cos(A+B)SinA} = 3{Sin(A+B)CosA + Cos(A+B)sinA}
Open the bracket
4Sin(A+B)CosA - 4Cos(A+B)SinA = 3Sin(A+B)CosA + 3Cos(A+B)sinA
Collecting like terms
4Sin(A+B)CosA - 3Sin(A+B)cosA = 3Cos(A+B)sinA + 4Cos(A+B)sinA
Sin(A+B)CosA = 7Cos(A+B)sinA
Divide both sides by sinA
Sin(A+B)CosA/sinA= 7Cos(A+B)sinA/sinA
Since cosA/sinA = cotA, the expression becomes;
Sin(A+B)cotA = 7Cos(A+B)
Finally, divide both sides of the resulting equation by sin(A+B)
Sin(A+B)cotA/sin(A+B) = 7Cos(A+B)/sin(A+B)
CotA = 7cot(A+B) Proved!
Two birds sit at the top of two different trees. The distance between the first bird and a birdwatcher on the ground is 32 feet. The distance between the birdwatcher and the second bird is 45 feet. A triangle is created from point Bird Watcher, point First Bird, and point Second Bird. Angle First Bird is a right angle, and angle Second Bird measures x degrees. What is the angle measure, or angle of depression, between this bird and the birdwatcher? Round your answer to the nearest tenth. 35.4° 44.7° 45.3° 54.6°
Answer:
Step-by-step explanation:
When you draw out that picture (and very good description, btw!) basically what you have is a right triangle that has a base of 32 and a hypotenuse of 45. The right angle is one of the base angles and x is the vertex angle. We need to find the vertex angle before we can find the angle of depression from the second bird to the watcher. The side of length 32 is opposite the angle x, and 45 is the hypotenuse, so the trig ratio we need is the only one that directly relates side opposite to hypotenuse, which is the sin ratio:
[tex]sin(x)=\frac{32}{45}[/tex] and
sin(x) = .711111111
Go to your calculator and hit the 2nd button then the sin button and on your screen you will see:
[tex]sin^{-1}([/tex]
and after that open parenthesis enter in your decimal .711111111 and hit equals. You should get an angle of 45.325. That's angle x. But that's not the angle of depression. The angle of depression is the one complementary to angle x.
Angle of depression = 90 - angle x and
Angle of depression = 90 - 45.325 so
Angle of depression = 44.67 or 44.7 degrees.
Answer:
Its 45.3!!!
Step-by-step explanation:
Can someone help me with this please it’s algebra 2
Answer:
7 8 9
Step-by-step explanation:
The height of a building model is 2% of its actual height. If the building
model is 3 feet tall, how tall is the actual building?
Answer:
x = 150 feets
Step-by-step explanation:
Given that,
The height of a building model is 2% of its actual height.
The building model is 3 feet tall, h = 3 feet
We need to find the height of the actual building. Let it is x.
According to question,
h = 2% of x
We have, h = 3 feet
So,
[tex]x=\dfrac{h}{2\%}\\\\x=\dfrac{3}{2/100}\\\\x=150\ \text{feet}[/tex]
So, the actual height of the building is 150 feets.
I am visiting my friend Janette in Bristol. My journey takes a total time of 1 hour 26 minutes. I travel by train for 34 minutes, then walk at a rate of 1/2 mile per 10 minutes. How many miles do I walk for?
Answer:
2.6 miles
Step-by-step explanation:
1 hour 26 minutes= 86 minutes
86-34=52 total walk time
52 minutes= 5*1/2 miles
=2.5 miles walked
and 2 minutes.
so we need to find 1/5 of 1/2
(1/2)/5=0.1 mile
2.5+0.1=2.6 miles
How can you change a rational number to a decimal? Can you give an exsample?
Answer:
1/2=0.5
Step-by-step explanation:
¼=0.25
¾=0.75
A rectangular prism has a volume of 864 cubic units. How many cubic unit will fill the volume of the solid if they were packed without any gaps or overlaps
Answer: 864.
Step-by-step explanation:
The volume of a rectangular prism has a volume equal to:
V = W*L*H
W = width
L = length
H = height
We know that the volume is equal to 864 cubic units.
This means that if we want to fill the prism such that there is no gap or overlap, we should use exactly 864 unit cubes.
Reduce any fractions to lowest terms. Don't round your answer, and don't use mixed fractions. 4x+4\leq9x+84x+4≤9x+8
Answer:
x ≥ -4/5
Step-by-step explanation:
Maybe you want to solve ...
4x+4 ≤ 9x +8
0 ≤ 5x +4 . . . . . subtract 4x+4
0 ≤ x +4/5 . . . . . divide by 5
-4/5 ≤ x . . . . . . . subtract 4/5
Answer:
x ≥−4/5
Step-by-step explanation:
Solve for x in the equation x squared + 11 x + StartFraction 121 Over 4 EndFraction = StartFraction 125 Over 4 EndFraction.
Answer:
Below
Step-by-step explanation:
● x^2 + 11x + 121/4 = 125/4
Substract 125/4 from both sides:
● x^2 + 11x + 121/4-125/4= 125/4 -125/4
● x^2 + 11x - (-4/4) = 0
● x^2 +11x -(-1) = 0
● x^2 + 11 x + 1 = 0
This is a quadratic equation so we will use the determinanant (b^2-4ac)
● a = 1
● b = 11
● c = 1
● b^2-4ac = 11^2-4*1*1 = 117
So this equation has two solutions:
● x = (-b -/+ √(b^2-4ac) ) / 2a
● x = (-11 -/+ √(117) ) / 2
● x = (-11 -/+ 3√(13))/ 2
● x = -0.91 or x = -10.9
Round to the nearest unit
● x = -1 or x = -11
The solutions are { -1,-11}
The solution of the equation x² + 11x + (121/4) = 125/4 will be 0.09 and negative 11.09.
What is the solution to the equation?The distribution of weights to the variables involved that establishes the equilibrium in the calculation is referred to as a result.
The equation is given below.
x² + 11x + (121/4) = 125/4
Simplify the equation, then the equation will be
4x² + 44x + 121 = 125
4x² + 44x + 121 - 125 = 0
4x² + 44x - 4 = 0
x² + 11x - 1 = 0
We know that the formula, then we have
[tex]\rm x = \dfrac{-b \pm \sqrt {b^2 - 4ac}}{2a}[/tex]
The value of a = 1, b = 11, and c = -1. Then we have
[tex]\rm x = \dfrac{-11 \pm \sqrt {11^2 - 4 \times 1 \times (-1)}}{2 \times 1}\\\rm x = \dfrac{-11 \pm \sqrt {121 +4}}{2 }\\x = \dfrac{-11 \pm \sqrt {125}}{2 }[/tex]
Simplify the equation, then we have
x = (- 11 ± 11.18) / 2
x = (-11 - 11.18) / 2, (-11 + 11.18) / 2
x = -11.09, 0.09
The solution of the equation will be 0.09 and negative 11.09.
More about the solution of the equation link is given below.
https://brainly.com/question/545403
#SPJ6
please can someone help me solve this.. please help!!
Step-by-step explanation:
Hello,
Firstly just look to triangle BDE,
Here, you will find that,
140° = y+80° {the exterior and opposite interior angle of a triangle is equal}.
or, y= 140°-80° {shifting 80° to another side and subtracting it.}
Therefore, the value of y is 60°.
now, let's simply work with line EB or EG. we get;
angle GEF + y=180° { being a linear pair}.
or, angle GEF + 60°= 180°
or, angle GEF = 180°-60°
Therefore, the value of angle GEF = 120°.
now, looking in triangle EFG, we get;
angle GEF + 35°+x= 180° { the sum of interior angle of a triangle is 180°}.
or, 120°+35°+ x= 180°
or, x= 180°- 155°
Therefore, the value of x is 25°.
now, lastly finding the value of "z"
We find that x= z {being vertical opposite angle}
or, z =25°
Therefore, the value of z is 25°.
So, the values are,
x=25°
y=60°
and z= 25°
Hope it helps...
PLEASE HELP, WILL GIVE BRAINLIEST IF CORRECT!!!! (08.06 MC) Mike and his friends bought cheese wafers for $2 per packet and chocolate wafers for $1 per packet at a carnival. They spent a total of $25 to buy a total of 20 packets of wafers of the two varieties. Part A: Write a system of equations that can be solved to find the number of packets of cheese wafers and the number of packets of chocolate wafers that Mike and his friends bought at the carnival. Define the variables used in the equations. (5 points) Part B: How many packets of chocolate wafers and cheese wafers did they buy? Explain how you got the answer and why you selected a particular method to get the answer. (5 points)
Answer:
x = 5 , y = 15
Step-by-step explanation:
You can solve this using substitution.
Let the quantity of cheese wafers be denoted by x and the quantity of chocolate wafers denoted by y
2x + 1y = 25
x + y = 20
These two equations are the answer to part A, (remember to include the above prompt which says what x and y denote).
For part B I used substitution because it was more applicable to the question then addition or elimination.
ACTUAL WORK
Set 2x + 1y = 25 equal to x
x = 25 - y / 2
Replace x with y in the second equation
(25 - y / 2) + y = 20
And solve for y
y = 15
Since we know what y is we can replace y in the second equation and find what x is
x + 15 = 20
Solve for x
x = 5
Answer:
5 Cheese Wafers and 15 Chocolate Wafers
Step-by-step explanation:
determine the image of the point p[-3,10) under the translation [5,-7]
[tex](-3+5,10-7)=(2,3)[/tex]
Please answer this question now in two minutes
Answer:
m∠C = 102°
Step-by-step explanation:
This diagram is a Quadrilateral inscribed in a circle
The first step is to determine what m∠B
is
The sum of opposite angles in an inscribed quadrilateral is equal to 180°
m∠D + m∠B = 180°
m∠B = 180° - m∠D
m∠B = 180° - 80°
m∠B = 100°
Second step is we proceed to determine the exterior angles of the circle
m∠ADC = 2 × m∠B
m∠ADC = 2 × 100°
m∠ADC = 200°
m∠ADC = m∠CD + m∠AD
m∠AD = m∠ADC - m∠CD
m∠AD = 200° - 116°
m∠AD = 84°
The third step is to determine m∠BAD
m∠BAD = m∠AD + m∠AB
m∠BAD = 84° + 120°
m∠BAD = 204°
The final step Is to determine what m∠C is
It is important to note that:
m∠BAD is Opposite m∠C
Hence
m∠C = 1/2 × m∠BAD
m∠C = 1/2 × 204
m∠C = 102°
solve this equation -2x+9=-5x-15
Answer:
x = -8
I hope this helps!
A ship drops its anchor into the water and creates a circular ripple. The radius of the ripple increases at
a rate of 50 cm/s. If the origin is used as the location where the anchor was dropped into the water.
Find the equation for the circle 12 seconds after the anchor is dropped
Please write all the steps it’s for my summer school test and I need it done quick as possible thanks.
Answer:
The equation for the circle 12 seconds after the anchor is dropped is x^2 + y^2 = 360,000
Step-by-step explanation:
To find the equation for the circle 12 seconds when the radius of the ripple increases at a rate of 50 cm/s, the circle radius will be;
50 * 12 = 600 cm
Then place the equation inform of Pythagoras equation which is;
x^2 + y^2 = r^2
Where r is the radius
x^2 + y^2 = 600^2
x^2 + y^2 = 360,000
Then, the equation for the circle 12 seconds after the anchor is dropped is x^2 + y^2 = 360,000
Need help please asap this is not asap but please still give an answer im stuck
Answer:
135 cubes
Step-by-step explanation:
First, find the volume of the box with the equation V = Bh, where B is the area of the base and h is the height.
V = (2.25)(0.75)(1.25)
V = 2.109375
Next, find the volume of one cube with the side length 1/4 with V = Bh:
V = (0.25)(0.25)(0.25)
V = 0.015625
Then, divide the volume of the box by the volume of one cube:
2.109375 / 0.015625
= 135
A zoo train ride costs $4 per adult and $1 per child. On a certain day, the total number of adults (a) and children (c) who took the ride was 27, and the total money collected was $60. What was the number of children and the number of adults who took the train ride that day, and which pair of equations can be solved to find the numbers? 1) 11 children and 16 adults Equation 1: a + c = 27 Equation 2: 4a + c = 60 2) 16 children and 11 adults Equation 1: a + c = 27 Equation 2: 4a + c = 60 3) 11 children and 16 adults Equation 1: a + c = 27 Equation 2: 4a − c = 60 4) 16 children and 11 adults Equation 1: a + c = 27 Equation 2: 4a − c = 60
Answer:
11 adults and 16 children
Step-by-step explanation:
a + c = 27 and 4a + c = 60
3a = 60 - 27 = 33
a= 11
so c = 16
need help will give 5 stars.
Answer:
t=0.64
Step-by-step explanation:
h = -16t^2 +4t +4
We want h =0 since it is hitting the ground
0 = -16t^2 +4t +4
Using the quadratic formula
a = -16 b = 4 c=4
-b ± sqrt( b^2 -4ac)
----------------------------
2a
-4 ± sqrt( 4^2 -4(-16)4)
----------------------------
2(-16)
-4 ± sqrt( 16+ 256)
----------------------------
-32
-4 ± sqrt( 272)
----------------------------
-32
-4 ± sqrt( 16*17)
----------------------------
-32
-4 ± sqrt( 16) sqrt(17)
----------------------------
-32
-4 ± 4 sqrt(17)
----------------------------
-32
Divide by -4
1 ± sqrt(17)
----------------------------
8
To the nearest hundredth
t=-0.39
t=0.64
Since time cannot be negative
t=0.64
Answer:
0.64
Step-by-step explanation:
0 = -16t^2 + 4t + 4
-4(4t^2 - t -1) = 0
t = [-(-1) +/- sqrt (1 - 4*4*-1)] / 8)
t = 0.64, -0.39
answer is 0.64
4x=24 solve equation
Answer:
x=6
Step-by-step explanation:
Rearrange:
Rearrange the equation by subtracting what is to the right of the equal sign from both sides of the equation :
4*x-(24)=0
Step by step solution :
STEP
1
:
Pulling out like terms
1.1 Pull out like factors :
4x - 24 = 4 • (x - 6)
Equation at the end of step
1
:
STEP
2
:
Equations which are never true
2.1 Solve : 4 = 0
This equation has no solution.
A a non-zero constant never equals zero.
Solving a Single Variable Equation:
2.2 Solve : x-6 = 0
Add 6 to both sides of the equation :
x = 6
One solution was found :
x = 6
Answer:
x= 24/ 4
Step-by-step explanation:
You can simplify it
x= 6/1 which is x= 6
If sin Θ = 5 over 6, what are the values of cos Θ and tan Θ?
Answer:
Check explanation
Step-by-step explanation:
Sin∅=5/6
Opp=5. Hyp=6
Adj= (√6²+5²)
= √11
Cos∅=(√11)/6
Tan∅=5/(√11)
Solve. 4x−y−2z=−8 −2x+4z=−4 x+2y=6 Enter your answer, in the form (x,y,z), in the boxes in simplest terms. x= y= z=
Answer:
(-2, 4, 2)
Where x = -2, y = 4, and z = 2.
Step-by-step explanation:
We are given the system of three equations:
[tex]\displaystyle \left\{ \begin{array}{l} 4x -y -2z = -8 \\ -2x + 4z = -4 \\ x + 2y = 6 \end{array}[/tex]
And we want to find the value of each variable.
Note that both the second and third equations have an x.
Therefore, we can isolate the variables for the second and third equation and then substitute them into the first equation to make the first equation all one variable.
Solve the second equation for z:
[tex]\displaystyle \begin{aligned} -2x+4z&=-4 \\ x - 2 &= 2z \\ z&= \frac{x-2}{2}\end{aligned}[/tex]
Likewise, solve the third equation for y:
[tex]\displaystyle \begin{aligned} x+2y &= 6\\ 2y &= 6-x \\ y &= \frac{6-x}{2} \end{aligned}[/tex]
Substitute the above equations into the first:
[tex]\displaystyle 4x - \left(\frac{6-x}{2}\right) - 2\left(\frac{x-2}{2}\right)=-8[/tex]
And solve for x:
[tex]\displaystyle \begin{aligned} 4x+\left(\frac{x-6}{2}\right)+(2-x) &= -8 \\ \\ 8x +(x-6) +(4-2x) &= -16 \\ \\ 7x-2 &= -16 \\ \\ 7x &= -14 \\ \\ x &= -2\end{aligned}[/tex]
Hence, x = -2.
Find z and y using their respective equations:
Second equation:
[tex]\displaystyle \begin{aligned} z&=\frac{x-2}{2} \\ &= \frac{(-2)-2}{2} \\ &= \frac{-4}{2} \\ &= -2\end{aligned}[/tex]
Third equation:
[tex]\displaystyle \begin{aligned} y &= \frac{6-x}{2}\\ &= \frac{6-(-2)}{2}\\ &= \frac{8}{2}\\ &=4\end{aligned}[/tex]
In conclusion, the solution is (-2, 4, -2)
Answer:
x = -2
y =4
z=-2
Step-by-step explanation:
4x−y−2z=−8
−2x+4z=−4
x+2y=6
Solve the second equation for x
x = 6 -2y
Substitute into the first two equations
4x−y−2z=−8
4(6-2y) -y -2 = 8
24 -8y-y -2z = 8
-9y -2z = -32
−2(6-2y)+4z=−4
-12 +4y +4z = -4
4y+4z = 8
Divide by 4
y+z = 2
z =2-y
Substitute this into -9y -2z = -32
-9y -2(2-y) = -32
-9y -4 +2y = -32
-7y -4 = -32
-7y =-28
y =4
Now find z
z = 2-y
z = 2-4
z = -2
Now find x
x = 6 -2y
x = 6 -2(4)
x =6-8
x = -2
I need help factoring this question, Factor 4(20) + 84.
Answer:
164
Step-by-step explanation:
B for brackets
O for of
D for division
M for multiplication
A for addition
S for subtraction
You first start with the brackets (20) and multiply with 4 which is equal to 80 and then add it to 84 which makes 164
I hope this helps
The graph of f(x) = StartRoot x EndRoot is reflected over the y-axis. Use the graphing calculator to graph this reflection. Which list contains three points that lie on the graph of the reflection? (–81, 9), (–36, 6), (–1, 1) (1, –1), (16, –4), (36, –6) (–49, 7), (–18, 9), (–1, 1) (1, –1), (4, –16), (5, –25)
Answer:
(–81, 9), (–36, 6), (–1, 1) are the correct three points.
Step-by-step explanation:
Given the function:
[tex]f(x) =\sqrt x[/tex]
Please refer to the attached image.
The green line shows the graph of actual function.
It is reflected over y axis.
The reflected graph is shown in black color in attached image.
When reflected over y axis, the sign of variable [tex]x[/tex] changes from Positive to Negative.
So, the resultant function becomes:
[tex]f(x)=\sqrt{-x}[/tex]
i.e. we will have to give the values of x as negative now.
so, the options in which value of x is negative are the possible answers only.
The possible answers are:
(–81, 9), (–36, 6), (–1, 1) and
(–49, 7), (–18, 9), (–1, 1)
Now, we will check the square root function condition.
In the 2nd option, (–18, 9) does not satisfy the condition.
So, the correct answer is:
(–81, 9), (–36, 6), (–1, 1)
Answer:
A on E2020
Step-by-step explanation:
:)
simpily 2^3×3^2=6^5
Answer:
2^3×3^2=6^5 equation is wrong because
2×2×2×3×3=72
6^5=6×6×6×6×6=36×36×6=7776
the two numbers are not equal
Mate, I think your question is wrong ! ;(
[tex]Corrected \\ Question...\\[/tex] (2^3)^2*(3^2)^3=6^5
A combination lock uses three numbers between 1 and 46 with repetition, and they must be selected in the correct sequence. Is the name of "combination lock" appropriate? Why or why not? Choose the correct answer below. A. No, because the multiplication counting rule would be used to determine the total number of combinations. B. Yes, because the combinations rule would be used to determine the total number of combinations. C. No, because factorials would be used to determine the total number of combinations. D. No, because the permutations rule would be used to determine the total number of combinations.
The correct answer is D. No because the permutations rule would be used to determine the total number of combinations.
Explanation:
The difference between a combination and a permutation is that in permutations the order is considered. This applies to the numbers in a lock because these need to be in order. Therefore, to analyze the permutations in a lock, the rule for permutations should be used. This includes the general formula P (n,r) =[tex]\frac{n!}{(n-r) !}[/tex]; in this, n is the number of objects and r refers to the objects used in a permutation. Thus, the term "combination" is inappropriate because this is a permutation, and the permutation rule should be used.
Evaluate the function below at x=5. Then, enter your solution. f(x)=3(2)^x
Answer:
Solution: f(5) = 96
Step-by-step explanation:
f(5) = 3(2)^5
f(5) = 3 (2 × 2 × 2 × 2 × 2)
f(5) = 3 (32)
f(5) = 96
Evaluate the following expression. −8 × (−10) −7× 1/−1
Answer:
87Step-by-step explanation:
[tex]-8\left(-10\right)-7 \times \frac{1}{-1}=87\\\\\mathrm{Apply\:rule}\:-\left(-a\right)=a\\\\=8\times \:10-7\times \frac{1}{-1}\\\\8\times \:10=80\\\\7\times \frac{1}{-1}=-7\\\\=80-\left(-7\right)\\\\\mathrm{Apply\:rule}\:-\left(-a\right)=a\\\\=80+7\\\\=87[/tex]