How many miles per gallon does Jessica's car get during the entire 20-mile trip?

Question

On her 10-mile trip to school. Jessica's car gets 50mpg of gas. On her way home, her car gets 40mpg. How many miles per gallon does Jessica's car get during the entire 20-mile trip?

Answer 1

Since she got 50 mpg on her way to school, the amount of gas used was 10/50 = 0.2 gallons. On the way home, since she got 40 mpg, the amount of gas used was 10/40 = 0.25 gallons. The total amount of gas used was then 0.45 gallons and the total distance was 20 miles so her gas mileage was 20/0.45 = 44.44 (or in fractional terms 44 4/9) miles per gallon