Example 2: Kevin is starting a lawn-mowing business. His equipment (lawn mower, edger, trailer and all)

costs $8000. In order to purchase the equipment, Kevin takes out a loan from the bank. The bank

agrees to loan him the $8000 as an interest only loan, this means they will charge him $100 per month

as interest of the loan until he is able to repay the $8000 in full. He leases some of his equipment from a

dealer, and he pays $60 per month for his leases. Kevin is paid $120 per month by each of his customers,

and his cost (in fuel and maintenance) per customer is $10 per month. Let x be the number of Kevin's

(monthly) customers. We shall follow these steps to find out the critical value of x at which Kevin's

business breaks even.

(a) Express the monthly revenue () as a function of . (This answer is NOT a number but a function!)

(b) Express the monthly cost () as a function of . (Only include the costs he pays every month!)

(Your answer here is a function as well)

(c) Express the monthly profit () as function of . (Your answer is a function as well!)

(c) Find the value of at which Kevin breaks even 10 months after starting his business (after the start

up cost is accounted for). Assume the equipment has no resale value.