Answer:
5.25 hours are expected
Explanation:
The driver's car contains 15 gallons of gas.
She will drive until she has a quarter tank left, which means she will use 3 quarters or 75%.
75% of 15 is 11.25, meaning she will use 11.25 gallons.
The car averages 28 miles per gallon, which means it can go
11.25 gallons * 28 miles/gallon = 315 miles
She travels an average of 60 miles per hour
315 miles / 60 miles/hour = 5.25 hours.
As this is the math world, this expects that the car is 100% efficient, there are exactly 15 gallons, and that it goes exactly 28 miles per gallon.