The gas turbine cycle of a combined gas-steam power plant has a pressure ratio of 8. Air enters the compressor at 290 K and the turbine at 1400 K. The combustion gases leaving the gas turbine are used to heat the steam at 15 MPa to 450oC in heat exchanger. The combustion gases leave the heat exchanger at 2740C. Steam expands in a high pressure turbine to a pressure of 3 MPa and is reheated in the combustion chamber to 500oC before it expands in a low pressure turbine to 10 kPa. The mass flow rate of steam is 30 kg/s. Assuming all compression and expansion processes to be isentropic, determine:

a. The mass flow rate of air in the gas turbine cycle.
b. The rate of total heat input.
c. The thermal efficiency of the combined cycle.