21. Gas mileage actually varies slightly with the driving speed of a car (as well as with highway vs. city driving). Suppose your car averages 28 miles per gallon on the highway if your average
speed Is 51 miles per hour, and it averages 17 miles per gallon on the highway if your average
speed is 68 miles per hour.

A. What is the driving time for a 1700-mile trip if you drive at a speed of 51 miles per
hour? What is the driving time at 68 miles per hour.

B. Assume a gasoline price of $3.39 per gallon. What is the gasoline cost for a 1700 mile
trip if you drive at an average speed of 51 miles per hour? What is the gasoline cost of
68 miles per hour?