Write an equation of the line that passes through (-4,3) and (0,6).
An equation is y =

Answer:

17 cm

Step-by-step explanation:

Since this is a right triangle, we can use the Pythagorean theorem

a^2 +b^2 = c^2  where a and b are the legs and c is the hypotenuse

8^2 + 15^2 =c^2

64+225 = c^2

289 = c^2

Take the square root of each side

sqrt(289) = sqrt(c^2)

17 = c

Answer:

The hypotenuse is 17cm

Step-by-step explanation:

Pythagoras theorem is :   [tex]a^{2} +b^{2} =c^{2}[/tex]

To work out the hypotenuse of this triangle you would first need to know Pythagoras theorem. The theorem states that [tex]a^{2} +b^{2} =c^{2}[/tex]. A and B are the 2 lengths given in this question and c is the hypotenuse.

The first step in working out the hypotenuse is to square the base of 8, this gives you 64.

Then you would need to square the height of 15, this gives you 225. This is because we are substituting the values into a and b.

Then the next step is to add the values of 64 and 225, this gives you 289.

The final step is to root the value of 289, which gives you 17cm. This is because as c is the hypotenuse while the value worked out is c squared and so to work out c you would have to root it.

1) Square the base of 8cm.

[tex]8^{2} =64[/tex]

2) Square the height of 15cm.

[tex]15^{2} =225[/tex]

3) Add 64 and 225.

[tex]64+225=289[/tex]

4) Root the value of 289.

[tex]\sqrt{289}= 17cm[/tex]

Step-by-step explanation:

I think 40 should be the first term in the sequence because it is given 40.. 6n - 1

Step-by-step explanation:

Step 1:  Solve using the first point

(2, 28)

[tex]28 = a(2)^3 + b(2)^2 + c(2) + d[/tex]

[tex]28 = 8a + 4b + 2c + d[/tex]

Step 2:  Solve using the second point

(-1, -5)

[tex]-5 = a(-1)^3 + b(-1)^2 + c(-1) + d[/tex]

[tex]-5 = -a + b - c + d[/tex]

Step 3:  Solve using the third point

(4, 220)

[tex]220 = a(4)^3 + b(4)^2 + c(4) + d[/tex]

[tex]220 = 64a + 16b + 4c + d[/tex]

Step 4:  Solve using the fourth point

(-2, -20)

[tex]-20 = a(-2)^3 + b(-2)^2 + c(-2) + d[/tex]

[tex]-20 = -8a + 4b - 2c + d[/tex]

Step 5:  Combine the first and fourth equations

[tex]28 - 20 = 8a - 8a + 4b + 4b + 2c - 2c + d + d[/tex]

[tex]8 = 8b + 2d[/tex]

[tex]8 - 8b = 8b - 8b + 2d[/tex]

[tex](8 -8b)/2 = 2d/2[/tex]

[tex]4 - 4b = d[/tex]

Step 6:  Solve for c in the second equation

[tex]-5 + 5 = -a + b - c + d + 5[/tex]

[tex]0 + c = -a + b - c + c + d + 5[/tex]

[tex]c = -a + b + d + 5[/tex]

Step 7:  Substitute d with the stuff we got in step 5

[tex]c = -a + b + (4 - 4b) + 5[/tex]

[tex]c = -a + b + 4 - 4b + 5[/tex]

[tex]c = -a - 3b + 9[/tex]

Step 8:  Substitute d and c into the first equation

[tex]28 = 8a + 4b + 2(-a - 3b + 9) + (4 - 4b)[/tex]

[tex]28 = 8a + 4b - 2a - 6b + 18 + 4 - 4b[/tex]

[tex]28 - 22 = 6a - 6b + 22 - 22[/tex]

[tex]6 / 6 = (6a - 6b) / 6[/tex]

[tex]1 + b = a - b + b[/tex]

[tex]1 + b = a[/tex]

Step 9:  Substitute a, b, and c into the third equation

[tex]220 = 64(1 + b) + 16b + 4(-(1 + b) - 3b + 9) + (4 - 4b)[/tex]

[tex]220 = 64 + 64b + 16b + 4(-1 - b - 3b + 9) + 4 - 4b[/tex]

[tex]220 - 100 = 60b + 100 - 100[/tex]

[tex]120 / 60 = 60b / 60[/tex]

[tex]2 = b[/tex]

Step 10:  Find a using b = 2

[tex]a = b + 1[/tex]

[tex]a = (2) + 1[/tex]

[tex]a = 3[/tex]

Step 11:  Find c using a = 3 and b = 2

[tex]c = -a - 3b + 9[/tex]

[tex]c = -(3) - 3(2) + 9[/tex]

[tex]c = -3 - 6 + 9[/tex]

[tex]c = 0[/tex]

Step 12:  Find d using b = 2

[tex]d = 4 - 4b[/tex]

[tex]d = 4 - 4(2)[/tex]

[tex]d = 4 - 8[/tex]

[tex]d = -4[/tex]

Answer:  [tex]a = 3, b = 2, c = 0,d = -4[/tex]

Answer:

a = 3

b = 2

c = 0

d = -4

Step-by-step explanation:

Form 4 equations and solve simultaneously

28 = a(2)³ + b(2)² + c(2) + d

28 = 8a + 4b + 2c + d (1)

-5 = -a + b - c + d (2)

220 = 64a + 16b + 4c + d (3)

-20 = -8a + 4b - 2c + d (4)

(1) + (4)

28 = 8a + 4b + 2c + d

-20 = -8a + 4b - 2c + d

8 = 8b + 2d

d = 4 - 4b

Equation (2)

c = -a + b + d + 5

c = -a + b + 4 - 4b+ 5

c = -a - 3b + 9

28 = 8a + 4b + 2c + d (1)

28 = 8a + 4b + 2(-a - 3b + 9) + 4 - 4b

28 = 6a - 6b + 22

6a - 6b = 6

a - b = 1

a = b + 1

220 = 64a + 16b + 4c + d (3)

220 = 64(b + 1) + 16b + 4(-b - 1 - 3b + 9) + 4 - 4b

220 = 60b + 100

60b = 120

b = 2

a = 2 + 1

a = 3

c = -3 - 3(2) + 9

c = 0

d = 4 - 4(2)

d = -4

Answer:

A 4* (7 - 3)

Step-by-step explanation:

Let's do this part by part. First we have "subtract 3 from 7:" this means we are taking 3 out of 7.

7 - 3

Next we have "then multiply by 4." So we need to take the above quantity and multiply the whole thing by 4.

(7-3) x 4

or

4 * (7-3)

The answer is A.

Answer:

He has to get a 98 on his last test

Step-by-step explanation:

Answer:

a) Each 1m² of fence panel costs: £2

b) I metre of wooden frame costs: £1

Step-by-step explanation:

Let the price of 1 sq.m. of fence panel be x

Let the price of 1 m of wooden frame be y

In Fig 1

Length = 4 m

Breadth = 3 m

Area =[tex]Length \times breadth = 4 \times 3 = 12 sq.m.[/tex]

Cost of 1 sq.m. = x

Cost of 12 sq.m. = 12x

Perimeter =2(l+b)=2(4+3)=14 m

Cost of 1 m of wooden frame = y

Cost of 14 m of wooden frame = 14y

We are given that total cost of framing and fencing is 38

So. 12x+14y=38 ----1

In Fig 2

Length = 6 m

Breadth = 2 m

Area =[tex]Length \times breadth = 6 \times 2 = 12 sq.m[/tex].

Cost of 1 sq.m. = x

Cost of 12 sq.m. = 12x

Perimeter =2(l+b)=2(6+2)=16 m

Cost of 1 m of wooden frame = y

Cost of 16 m of wooden frame = 16y

We are given that total cost of framing and fencing is 40

So. 12x+16y=40---2

Substitute the value of 12x form 1 in 2

38-14y+16y=40

2y=2

y=1

Substitute the value of y in 2

12x+16=40

12x=24

x=2

So, cost of 1 sq.m. of fence panel is 2 and cost of 1 m of wooden frame is 1

In fig 3

To verify :

Length = 3 m

Breadth = 5 m

Area = [tex]Length \times breadth = 3 \times 5 = 15 sq.m.[/tex]

Cost of 1 sq.m. = 2

Cost of 12 sq.m. =[tex]15 \times 2 = 30[/tex]

Perimeter =2(l+b)=2(3+5)=16 m

Cost of 1 m of wooden frame = 1

Cost of 16 m of wooden frame = 16

So, Total cost = 30+16=46

We are given that cost of fencing and framing is 46

Thus verified

Hence

a) Each 1m² of fence panel costs: £2

b) I metre of wooden frame costs: £1

Answer:

a = 3

b = 2

c = 0

d = -4

Step-by-step explanation:

Form 4 equations and solve simultaneously

28 = a(2)³ + b(2)² + c(2) + d

28 = 8a + 4b + 2c + d (1)

-5 = -a + b - c + d (2)

220 = 64a + 16b + 4c + d (3)

-20 = -8a + 4b - 2c + d (4)

(1) + (4)

28 = 8a + 4b + 2c + d

-20 = -8a + 4b - 2c + d

8 = 8b + 2d

d = 4 - 4b

Equation (2)

c = -a + b + d + 5

c = -a + b + 4 - 4b+ 5

c = -a - 3b + 9

28 = 8a + 4b + 2c + d (1)

28 = 8a + 4b + 2(-a - 3b + 9) + 4 - 4b

28 = 6a - 6b + 22

6a - 6b = 6

a - b = 1

a = b + 1

220 = 64a + 16b + 4c + d (3)

220 = 64(b + 1) + 16b + 4(-b - 1 - 3b + 9) + 4 - 4b

220 = 60b + 100

60b = 120

b = 2

a = 2 + 1

a = 3

c = -3 - 3(2) + 9

c = 0

d = 4 - 4(2)

d = -4

Step-by-step explanation:

Step 1:  Solve using the first point

(2, 28)

[tex]28 = a(2)^3 + b(2)^2 + c(2) + d[/tex]

[tex]28 = 8a + 4b + 2c + d[/tex]

Step 2:  Solve using the second point

(-1, -5)

[tex]-5 = a(-1)^3 + b(-1)^2 + c(-1) + d[/tex]

[tex]-5 = -a + b - c + d[/tex]

Step 3:  Solve using the third point

(4, 220)

[tex]220 = a(4)^3 + b(4)^2 + c(4) + d[/tex]

[tex]220 = 64a + 16b + 4c + d[/tex]

Step 4:  Solve using the fourth point

(-2, -20)

[tex]-20 = a(-2)^3 + b(-2)^2 + c(-2) + d[/tex]

[tex]-20 = -8a + 4b - 2c + d[/tex]

Step 5:  Combine the first and fourth equations

[tex]28 - 20 = 8a - 8a + 4b + 4b + 2c - 2c + d + d[/tex]

[tex]8 = 8b + 2d[/tex]

[tex]8 - 8b = 8b - 8b + 2d[/tex]

[tex](8 -8b)/2 = 2d/2[/tex]

[tex]4 - 4b = d[/tex]

Step 6:  Solve for c in the second equation

[tex]-5 + 5 = -a + b - c + d + 5[/tex]

[tex]0 + c = -a + b - c + c + d + 5[/tex]

[tex]c = -a + b + d + 5[/tex]

Step 7:  Substitute d with the stuff we got in step 5

[tex]c = -a + b + (4 - 4b) + 5[/tex]

[tex]c = -a + b + 4 - 4b + 5[/tex]

[tex]c = -a - 3b + 9[/tex]

Step 8:  Substitute d and c into the first equation

[tex]28 = 8a + 4b + 2(-a - 3b + 9) + (4 - 4b)[/tex]

[tex]28 = 8a + 4b - 2a - 6b + 18 + 4 - 4b[/tex]

[tex]28 - 22 = 6a - 6b + 22 - 22[/tex]

[tex]6 / 6 = (6a - 6b) / 6[/tex]

[tex]1 + b = a - b + b[/tex]

[tex]1 + b = a[/tex]

Step 9:  Substitute a, b, and c into the third equation

[tex]220 = 64(1 + b) + 16b + 4(-(1 + b) - 3b + 9) + (4 - 4b)[/tex]

[tex]220 = 64 + 64b + 16b + 4(-1 - b - 3b + 9) + 4 - 4b[/tex]

[tex]220 - 100 = 60b + 100 - 100[/tex]

[tex]120 / 60 = 60b / 60[/tex]

[tex]2 = b[/tex]

Step 10:  Find a using b = 2

[tex]a = b + 1[/tex]

[tex]a = (2) + 1[/tex]

[tex]a = 3[/tex]

Step 11:  Find c using a = 3 and b = 2

[tex]c = -a - 3b + 9[/tex]

[tex]c = -(3) - 3(2) + 9[/tex]

[tex]c = -3 - 6 + 9[/tex]

[tex]c = 0[/tex]

Step 12:  Find d using b = 2

[tex]d = 4 - 4b[/tex]

[tex]d = 4 - 4(2)[/tex]

[tex]d = 4 - 8[/tex]

[tex]d = -4[/tex]

Answer:  [tex]a = 3, b = 2, c = 0,d = -4[/tex]

Answer:

C

Step-by-step explanation:

It cannot be A because it is a parabola, and what that means is the x^2. So, we can immediately eliminate that. This is because if you do a sketch of it it was the "U" shape. I am not positive, but I think that it is C because of the pattern going on in the y-coordinate. It goes +2, +4, then presumably +6. So then the (0,y) is (0,12). This would mean that the equation would end with +12. That is why C is the best choice. I hope that answered your question, and is correct!

Answer:

a)

Theoretical: 10/30 = 1/3

Experimental: 12/30 = 6/15

Step-by-step explanation:

the theoretical probability is if every number was rolled an equal amount of times. as there are 3 options and a number was chosen 30 times, if we divide 30 by 3 we will get the theoretical probability of choosing a 2

30 ÷ 3 = 10

the theoretical probability = 10/30 or simplified 1/3

the experimental probability is the result when one of the numbers from

1 to 3 were actually randomly selected 30 times. the chart shows that the 2 was selected 12 times out of 30 therefore the experimental probability = 12/30 or simplified 6/15

Theoretical:

fraction: 1/3

decimal: 0.33∞

percentage: 33%

Experimental:

fraction: 6/15

decimal: 0.4

percentage: 40%

I hope this was helpful :-)

Multiply both sides by 9.

x/9 = 3

(x/9) * (9) = (3) * (9)

x=27

The solution of the expression x/9 = 3 is,

⇒ x = 27

To multiply means to add a number to itself a particular number of times. Multiplication can be viewed as a process of repeated addition.

We have to given that;

The expression is,

⇒ x/9 = 3

Now, Simplify the expression as;

⇒ x/9 = 3

Multiply by 9, we get;

⇒ 9 × x/9 = 9 × 3

⇒ x = 27

Thus, The solution is,

⇒ x = 27

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Answer:

49.3%

Step-by-step explanation:

37 / 75  = 49.3%

The answer is 49.3%.

Probability is the ratio of the number of outcomes in an exhaustive set of equally likely outcomes that produce a given event to the total number of possible outcomes.

How to find that at least 7 will be girls?

Given that 75 babies are born assume that boys and girls are equally probable.

Then the probability that at least 37 will be girls is

37 / 75  = 49.3%.

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Answer:

$5.65

Step-by-step explanation:

1.29 x 3 + 0.89 x 2= $5.65

:3

Answer:

3/8

Step-by-step explanation:

Answer:

3/8

Step-by-step explanation:

Answer:

1. 20 + 2x ≤ 60

2. Yes, see explanation

Step-by-step explanation:

Let x equal the amount of exercises Anna can perform.

The inequality will look like this:

20 + 2x ≤ 60

Let's go over each of the values and why there in the equation.

20: The amount of minutes Anna has already spent in the gym

2: The amount of minutes per exercise

x: The amount of exercises Anna can perform

≤: The amount of exercises must be less than or equal to the amount of time Anna is willing to spend in the gym.

60: The amount of minutes in an hour; the amount of time Anna is willing to spend at the gym.

Now, plug in 18 for x for question 2.

20 + 2(18) ≤ 60

Evaluating 2*18, the inequality becomes 20 + 36 ≤ 60.

Evaluating 20 + 36, the inequality becomes 56 ≤ 60.

Since 56 is less than 60, we can determine that Anna has time to do 18 more exercises.

Answer:10x^2+11xy-6y^2

Step-by-step explanation:

( 2 x + 3 y ) ( 5 x − 2 y )  = 2 x ( 5 x − 2 y ) + 3 y ( 5 x − 2 y )

= 10 x 2 − 4 x y + 15 x y − 6y 2

= 10 x 2 + 11 x y -6 y 2 .

Answer:

40°

Step-by-step explanation:

complementary angels makes the sum of two angles = 90°

so

<ABC + < CBD = 90°

if <ABC = 50°

then 90° - 50° = 40°

So the right answer is of option B.

Look at the attached picture

hope it will be helpful to you...

Answer:

The second one

Step-by-step explanation:

Answer:

3.5

Step-by-step explanation:

1 / 3

First, let's find the mean.

\dfrac{26+31+39+32}{4} = \dfrac{128}{4}= \blueD{32} \text{ putts}  

4

26+31+39+32

​  

=  

4

128

​  

=32 puttsstart fraction, 26, plus, 31, plus, 39, plus, 32, divided by, 4, end fraction, equals, start fraction, 128, divided by, 4, end fraction, equals, start color #11accd, 32, end color #11accd, start text, space, p, u, t, t, s, end text

Hint #22 / 3

Next, let's find the distance each data point is from the mean.

Data point Distance from the mean

262626 \blueD{32}-26 = 632−26=6start color #11accd, 32, end color #11accd, minus, 26, equals, 6

313131 \blueD{32}-31 = 132−31=1start color #11accd, 32, end color #11accd, minus, 31, equals, 1

393939 39-\blueD{32} = 739−32=739, minus, start color #11accd, 32, end color #11accd, equals, 7

323232 32-\blueD{32} = 032−32=032, minus, start color #11accd, 32, end color #11accd, equals, 0

Hint #33 / 3

The mean absolute deviation (MAD) is the mean of the distances from the mean.

\dfrac{6+1+7+0}{4} = \dfrac{14}{4}= 3.5\text{ putts}  

4

6+1+7+0

​  

=  

4

14

​  

=3.5 putts  I hope it helps.

Answer:

Step-by-step explanation:

Let x be the random variable representing the length of an oarfish. Since it is normally distributed and the population mean and population standard deviation are known, we would apply the formula,

z = (x - µ)/σ

Where

x = sample mean

µ = population mean

σ = standard deviation

The given probability value is 16% = 0.16. From the normal distribution table, the z score corresponding to the probability value is - 0.99

This indicates that the sample mean is lower than the population mean

Therefore,

- 0.99 = (x - 6.5)/1.5

- 0.99 × 1.5 = x - 6.5

- 1.5 = x - 6.5

x = - 1.5 + 6.5

x = 5m

The correct answer is

oarfish that are shorter than 5 m

Answer:

oarfish that are shorter than 5

oarfish that are longer than 8 m

I Just took the test!

Answer:

The return on investment in dollar terms is $700

The return on investment as a percentage of cost of investment is 7%

Step-by-step explanation:

The return on investment is the value of the investment when liquidated minus the initial amount invested

Liquidated amount is $10,700

initial cost is $10,000

return on investment in dollar terms=$10,700-$10,000=$700

return on investment in % terms=dollar return on investment/initial cost of investment

dollar return is $700

initial cost of investment is $10,000

return on investment in % terms=$700/$10,000=7%

Answer:

B. 90

Step-by-step explanation:

In a triangle if one of the angle is 90 deg the triangle is said to be a RIGHT ANGLED TRIANGLE.

Hope this helps, Pls Mark me as Brainliest!!!

Given triangle is a right-angle triangle. option B is correct.

The properties of the triangle are:

1. The sum of all the angles of a triangle (of all types) is equal to 180°.

2. The sum of the length of the two sides of a triangle is greater than the length of the third side.

3. In the same way, the difference between the two sides of a triangle is less than the length of the third side.

A triangle is said to have a right angle if one of its angles is precisely 90 degrees. There are several techniques to spot a right angle triangle, including:

Therefor, the given triangle is a right-angle triangle.

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Answer:

q > 27/61

Step-by-step explanation:

50q + 43 > -11q +70

Add 11 q to each side

50q+11q + 43 > -11q+11q +70

61q +43 > 70

Subtract 43 from each side

61q+43-43 > 70-43

61q > 27

Divide each side by 61

61q/61 >27/61

q > 27/61

Answer:

q > 27/61

Step-by-step explanation:

hope this helps!!

Answer:

negative 3

Step-by-step explanation:

Mark brainlest

Epert verifyied

Answer:

[tex]{f}^{ - 1}(x) = \frac{x + 11}{ - 5} [/tex]

Step-by-step explanation:

[tex]f(x) = - 5x - 11 \\ - 5x - 11 =x \\ - 5x = x + 11 \\ {f}^{ - 1}(x) = \frac{x + 11}{ - 5} [/tex]

Answer:

3

Step-by-step explanation:

[tex]\sqrt{648} =\sqrt{2 * 2 * 2 * 3 * 3 * 3 * 3} \\\\=\sqrt{2^{3}*3^{4}}[/tex]

a = 3 & b =4

Answer:

c is 120 degrees

Answer:

The reference angle is the acute angle formed by the terminal side of an angle in standard position and the x-axis

Step-by-step explanation:

-440° will be in the 1st quadrant

We solve by adding 360° to it till it becomes positive

-440°+360°= -80°

-80°+360°=280°

The equivalent value will become

360°-280°= 80°

Answer:

The reference angle for an angle whose measure is -440° is 80°.

Step-by-step explanation:

The cycles for angles range from the traditional 0° to 360° and subsequent 360° ranges befor and after this traditional intervals, also have the same properties.

So, the ranges that exist and correspond to the traditional 0° to 360° include

0° to 360°

360° to 720°

720° to 1080°

And in the negative direction, we have

-360° to 0°

-720° to -360°

We can see that -440 is in the range of

-720° to -360°

Using the traditional 0° to 360° to compare this range of -720° to -360°, let x represent the reference angle in the traditional range that we require.

-720° ------ 0°

-440° ------ x

-360° ------ 360°

Using interpolation,

[-440° - (-720°)]/[-360° - (-440°)] = (x - 0°)/(360° - x)

(280/80) = x/(360-x)

3.5 = x/(360-x)

3.5(360 - x) = x

1260° - 3.5x = x

4.5x = 1260°

x = (1260°/4.5) = 280°

But, the reference angle is the smallest angle that one can make from the terminal side of an angle (that is, where the angle ends) with the x-axis. It uses the x-axis as its frame of reference.

So, 280° is a fourth quadrant angle, whose equivalent in the first quadrant is 360° - 280° = 80°

Hope this Helps!!!

Answer:

B, C, E, F

Step-by-step explanation:

x^2 >= 49

A. 6: 6^2 = 36 No

B. 20: 20^2 = 400 Yes

C. -7: (-7)^2 = 49 Yes

D. -5: (-5)^2 = 25 No

E. -16: (-16)^2 = 256 Yes

F. 7: 7^2 = 49 Yes

Answer:

Options B and D.

Step-by-step explanation:

The general form of sine function

[tex]h(x)=A\sin (Bx+C)+D[/tex]

where, |A| is amplitude, [tex]\frac{2\pi}{B}[/tex] is period, [tex]\frac{-C}{B}[/tex] is phase shift and D is y-intercept.

The general form of cosine function

[tex]h(x)=A\cos (Bx+C)+D[/tex]

where, |A| is amplitude, [tex]\frac{2\pi}{B}[/tex] is period, [tex]\frac{-C}{B}[/tex] is phase shift and D is y-intercept.

In function, [tex]f(x)=-\sin x-1[/tex]

Amplitude : [tex]|A|=1[/tex]

y-intercept : -1

In function, [tex]f(x)=-2\sin x-1[/tex]

Amplitude : [tex]|A|=2[/tex]

y-intercept : -1

In function, [tex]f(x)=-\cos x[/tex]

Amplitude : [tex]|A|=1[/tex]

y-intercept : 0

In function, [tex]f(x)=-2\cos x-1[/tex]

Amplitude : [tex]|A|=2[/tex]

y-intercept : -1

Therefore, the correct options are B and D.

Answer:

B

Step-by-step explanation:

edge2020 quiz

Answer:

6550

Step-by-step explanation:

You can put this solution on YOUR website!

Call the number of hardcover and paperback books, h and p.

Thus  

h + p = 8 and the value equation is

4h + 2p = 26

Now multiply the top one by four and subtract from the second one...we get

4h + 2p = 26

-(4h + 4p = 32)

----------------

-2p = -6

p = 3 so that

h = 5   x +  y = 8,    (1)

4x + 2y = 26,   (2)

where x and y are the numbers of hardcover and softcover books respectively.

To solve, multiply the equation (1) by 2 (both sides) and then distract it from the equation (2). You will get

4x - 2x = 26 - 16,   or

2x = 10,   or   x = 5 - the number of hardcover books purchased.

Then from the equation (1) you get y = 3.

Check. 4*x + 2*3 = 4*5 + 2*3 = 26. OK.