Answer: There are 75 books.
Price of each book = $4.
Step-by-step explanation:
Let x = Number of books in the box.
Then as per given,
Cost of x books = $300
Cost of one book = 
Books left after giving 15 of them = x-15
Selling price of (x-15) books= $330
Selling price of one book = 
Profit on each book= $1.50
Profit = selling price - cost price
![\Rightarrow 1.50=\dfrac{330}{x-15}-\dfrac{300}{x}\\\\\Rightarrow\ 1.50=\dfrac{330(x)-300(x-15)}{x(x-15)}\\\\\Rightarrow\ 1.50=\dfrac{330x-300x+4500}{x^2-15x}\\\\\Rightarrow\ 1.50(x^2-15x)=30x+4500\\\\\Rightarrow\ 1.50x^2-22.5x=30x+4500\\\\\Rightarrow\ 1.50x^2-52.5x-4500=0\\\\\Rightarrow\ 1.50x^2-52.5x-4500=0\\\\\Rightarrow\ x^2-25x-3000=0\ \ [\text{divide by 1.5}]](https://tex.z-dn.net/?f=%5CRightarrow%201.50%3D%5Cdfrac%7B330%7D%7Bx-15%7D-%5Cdfrac%7B300%7D%7Bx%7D%5C%5C%5C%5C%5CRightarrow%5C%201.50%3D%5Cdfrac%7B330%28x%29-300%28x-15%29%7D%7Bx%28x-15%29%7D%5C%5C%5C%5C%5CRightarrow%5C%201.50%3D%5Cdfrac%7B330x-300x%2B4500%7D%7Bx%5E2-15x%7D%5C%5C%5C%5C%5CRightarrow%5C%201.50%28x%5E2-15x%29%3D30x%2B4500%5C%5C%5C%5C%5CRightarrow%5C%201.50x%5E2-22.5x%3D30x%2B4500%5C%5C%5C%5C%5CRightarrow%5C%201.50x%5E2-52.5x-4500%3D0%5C%5C%5C%5C%5CRightarrow%5C%201.50x%5E2-52.5x-4500%3D0%5C%5C%5C%5C%5CRightarrow%5C%20x%5E2-25x-3000%3D0%5C%20%5C%20%5B%5Ctext%7Bdivide%20by%201.5%7D%5D)

Number of books cannot be negative.
So, there are 75 books.
Price of each book = 
So price of each book = $4.
Answer:
Isosceles
Step-by-step explanation:
In order to figure what type of triangle this is out, we need to start by plotting the given points. That will help us visualize the triangle better and see if our conclusions make sense. (See attached picture).
Once we got the triangle, the strategy to follow is to use the distance between two points formula to see what the measurement of each side of the triangle is. This will help us determine if 2, 3 or none of the sides of the tirangle are the same.
The distance formula is the following:

so now we can find the desired distances, let's start with the distance between P and Q:

which yields:

next, let's find the distance between P and R:

which yields:

and finally the distance between Q and R:

which yields:

As you may see from the result, only two of the three sides are the same, |PQ| and |PR|, so this will be an Isosceles triangle.
If the perimeter is 90 feet and on side is 26 feet then the width of the playground is 38 feet
Answer:
Step-by-step explanation:
23). By applying triangle sum theorem in the given triangle,
(x + 83)° + (x + 48)° + 65° = 180°
2x + 196 = 180
2x = -16
x = -8
Measure of angle A = x + 48
= -8 + 48
= 40°
Therefore, Option A is the answer.
24). By triangle sum theorem,
(3x + 14)° + 90° + (4 + 3x)° = 180°
6x + 108 = 180
6x = 72
x = 12
Measure of angle A = (4 + 3x)
= 4 + 3(12)
= 40°
Therefore, Option A is the answer.