Help Solving Gas Turbine Problem with Polytropic Expansion

[sa1066]

hey can anyone help me with this problem...

three pounds-mass per second of air is reversibly and polytropically (n=1.48) expanded in a gas turbine from 2100F to 900F. if the exhaust pressure is 15psia, determine the work produced per pound-mass of air, the power generated, and the rate of heat transfer.

i...dont...understand...what...this...means...

thank you

 

[sa1066]

So, yeah, I'm attempting to help my nephew out with this; however, my knowledge of physics is limited (haven't studied in a number of years). If any person is willing to at least assist me with a starting point or a formula to follow that would be great.