Tom put 18 gallons of midgrade gas in his truck and filled up his empty five gallon gas tank with regular
gas for his lawnmower at home. he spent $59.91. the following week, he put 14 gallons of midgrade
gas in his truck and topped off his five gallon tank with just one gallon of regular gas. if he paid $39.75
and the prices remained the same, find the price per gallon of midgrade and regular gas.