An airplane begins a flight with a total of 36.0 gal. of fuel stored in two separate wing tanks. During the flight, 25.0% of the fuel in one tank is used, and in the other tank, 37.5% of the fuel is used. If the total fuel used is 11.2 gal. find the amounts x and y stored in each tank.

Just build a small two variable system of equations.

x= amount in tank 1, y=amount in tank 2.

Total fuel: x+y=36

Fuel used: .25x+.375y=11.2

Solve away.