The gas passing through the turbine of a simple ideal Brayton cycle has the volumetric composition 20 percent nitrogen, 5 percent oxygen, 40 percent carbon dioxide, and 35 percent water. Calculate the thermal efficiency of this cycle when the air enters the compressor at 10 psia and 408F; the pressure ratio is 6; and the temperature at the turbine inlet is 1400oF. Model the heat-addition and heat-rejection processes using constant gas properties that are the average of the air and turbine gas properties.