a certain car uses 12 gallons of gasoline in traveling 180 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 ?
"180 / 10 = 18 . the difference is 18 - 15 = 3 . answer b"
subtract(divide(180, 10), divide(180, 12))