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.
I only know what in the picture which is the letter A
Answer:
2.8 hours
Step-by-step explanation:
Distance = rate * time
If the west-bound train travels at a rate of 80 mph for t hours, then the distance it travels is 80t.
If the east-bound train travels at a rate of 90 mph for t hours, then the distance it travels is 90t.
The distance between the trains after t hours is 476; therefore, the distance of the west-bound train plus the distance of the east-bound train equals the total distance between them, 476:
80t + 90t = 476 and
170t = 476 so
t = 2.8 hours
Answer:
D
Step-by-step explanation:
gradient for the line y=5x+2 = 5 from y=mx+c where m =gradient
parallel lines have equal gradients thus M2=5
equation for line passing through point (-6,-1) and gradient , m=5 will be
(change in y/change in x)=M2
(y--1/x--6)=5
y+1/x+6 =5
y+1=5(x+6)
y+1=5x+30
y=5x+29
