Air at 540 F, 60 lbf/in 2 with a volume flow 40 ft3/s runs through an adiabatic

Question:

Air at 540 F, 60 lbf/in 2 with a volume flow 40 ft3/s runs through an adiabatic turbine with exhaust pressure of 15 lbf/in 2. Neglect kinetic energies and use constant specific heats. Find the lowest and highest possible exit temperature. For each case find also the rate of work and the rate of entropy generation.