You suspect that one of the cars in the fleet you are responsible for is burning gas at an unusually high rate. you want to calculate the gas mileage of the car during a 3-day trip from seattle to san francisco. when the trip started the odometer mileage was 12,956. it was 13,256 at the end of the trip. the driver turned in two gas receipts. the first time he stopped the gas was $2.99 per gallon and the cost was $42.08. the second time gas was $2.85 per gallon and the cost was $46.12. the gas gauge was at the same level for the beginning of the trip and at the end. what is your gas mileage?