A compact car can be rented from firm A for $160 per week with no charge for mileage or from firm B for $100 per week plus 20 cents for each mile driven. If the car is driven m miles, for what values of m does it cost less to rent from firm A?
Firm A's cost, with UNLIMITED miles: $160
Firm B's cost, with "m" miles driven: .2m + 100
We then get the following INEQUALITY: 160 < .2m + 100
Solve that to get m > 300, which means that, for Firm A to cost less than Firm B, one has to drive more than 300 miles.