#### Answer

a.) -88 dollars
b.) 599.50 dollars
c.) 755 books

#### Work Step by Step

There are three questions to answer here:
a. Find the profit if you sell 75 books.
b. Find the profit if you sell 200 books.
c. How many books must you sell to make $3600 in
profit?
We are given the formula, P = 5.5b - 500.5, where P = profit and b = amount of books sold.
So, for question "a":
P = 5.5b - 500.5
P = 5.5 × 75 - 500.5
P = 412.5 - 500.5
P = -88
For question "b":
P = 5.5b - 500.5
P = 5.5 × 200 - 500.5
P = 1,100 - 500.5
P = 599.5
For question "c":
P = 5.5b - 500.5
3,600 = 5.5b - 500.5
4,150.5 = 5.5b
b = 754.636...
Rationally, this answer means one must sell 755 whole books to break 3,600 dollars.