Question: A small corner store owner decides to advertise on local radio in order to help stimulate his sales. Radio station CFAL charges him a flat rate of $99, plus $20 per day for advertising. From the onset of the advertising the revenue increase can be described as (120 - x) dollars per day where x is the number of days the ad is run. He plans to run the ad for only 60 consecutive days.

a. How many days must the ad run until the increased revenue just covers the cost of the advertising?

b. How many days should he let the ad run in order to maximize his profit from the ad campaign?

c. What is the maximum profit?