A cylinder fitted with a piston has an initial volume of 2 ft^3 and contains nitrogen at 20 lbf/in^2, at 80 F (degrees). The piston is moved, compressing the nitrogen until the pressure is 160 lbf/in^2. and the temperature is 300 F. During this compression process heat is transfered from the nitrogen, and the work done on the nitrogen is 9.15 Btu. Starting from basic principels, determine the amount of the heat transfer.