Question 19
At the beginning of a trip, the mileage odometer read $56{,}200$ miles. The driver filled the gas tank with $6$ gallons of gasoline. During the trip, the driver filled the tank again with $12$ gallons of gasoline when the odometer read $56{,}560.$ At the end of the trip, the driver filled the tank again with $20$ gallons of gasoline; the odometer read $57{,}060.$ To the nearest tenth, what was the car’s average miles-per-gallon for the entire trip?