Question: Cell phone Plan A charges a flat monthly fee of $30.00 for the first 400 minutes, plus $0.07 for each minute > 400. Plan B charges a flat monthly fee of $45.00 for the first 600 minutes, plus $0.19 for each minute > 600. You know you will use more than 600 minutes per month.
a. At what number of minutes do the plans cost the same amount per month, and what is that amount?
b. Above this number of minutes, which plan is more expensive?