Air is used as the working fluid in a simple Bryaton cycle that has a pressure ratio of 12, a compressor inlet temperature of 300 K, and a turbine inlet temperature of 1000 K. Determine the required mass flow rate of air for a net power output of 90 MW, assuming both the compressor and the turbine have an isentropic efficiency of (a) 100% and (b) 80%. Assume constant specific heats at room temperature.