An insulated gas turbine receives a mixture of 10% CO2, 10% H2O and 80% N2 on a mole basis at 1800 R, 75 lbf/in 2. The volume flow rate is 70 ft3/s and its exhaust is at 1300 R, 15 lbf/in 2. Find the power output in Btu/s using constant specific heat from C.4 at 540 R.