Our hardware store buys tools for $15 each, marks them up and sells them for $30. Their monthly expenses (fixed costs) are $10,000.

a. What is the cost function?

b. What is the revenue?
c. How many units must be sold for the company to get a profit?

C(x) = 10000 + 15x

R(x) = 30x

set R >= C and solve for x