revenue? What are the values for demand and revenue at this price?

There is a fixed cost of $50,000 to start a production process. Once the process has
begun, the variable cost per unit is $25. The revenue per unit is projected to be $45.
a. Write an expression for total cost.
b. Write an expression for total revenue.
c. Write an expression for total profit.
d. Find the break-even point.

An author has received an advance against royalties of $10,000. The royalty rate is
$1.00 for every book sold in the United States, and $1.35 for every book sold outside
the United States. Define variables for this problem and write an expression that could
be used to calculate the number of books to be sold to cover the advance.
Let x1 = the number of books sold in the U.S.
Let x2 = the number of books sold outside the U.S.
10000 = 1x1 + 1.35x2
A university schedules summer school courses based on anticipated enrollment. The
cost for faculty compensation, laboratories, student services, and allocated overhead
for a computer class is $8500. If students pay $420 to enroll in the course, how large
would enrollment have to be for the university to break even?
Enrollment would need to be 21 students.
As part of their application for a loan to buy Lakeside Farm, a property they hope to