If you would like to know how many gallons remain to be used, you can do this using the following steps:
lost: 2% of 280 gallons = 2% * 280 gallons = 2/100 * 280 = 5.6 gallons
280 gallons - 5.6 gallons = 274.4 gallons
The correct result would be 274.4 gallons.
