Question

One phone company charges $12 per month plus $.05 per minute after the first 500 minutes. A second phone company charges $10 per month plus $.04 per minute after the first 300 minutes. How many minutes would a subscriber have to use so that the cost of the two plans is the same for a given month

Answer 1

you want x minutes, where

12+.05(x-500) = 10+.04(x-300)
x = 1100