a certain car uses 12 gallons of gasoline in traveling 120 miles . in order for the car to travel the same distance using 10 gallons of gasoline , by how many miles per gallon must the car ’ s gas mileage be increased ?
120 / 10 = 12 . the difference is 12 - 10 = 2 . answer a
subtract(divide(120, 10), divide(120, 12))