A quantity of gas with an initial volume of 1 cubic foot and a pressure of 2500 pounds per square foot expands to a volume of 3 cubic feet. Find the work done by the gas for the given volume. Assume that the pressure is inversely proportional to the volume.

work is the product of the pressure(p)and the volume(V)during a change of volume.

W=p*dw

i am unable to find change in volume..?