Air enters a turbine of an air-standard Brayton cycle at 1000 kPa, 1000 K, and expands to 100 kPa in two stages. The air is reheated between the stages at a constant pressure of 400 kPa to 1000 K. A regenerator with an effectiveness of 80% is also used in the cycle. Assuming variable specific heat, with an enthalpy of 500 kJ/kg for state 2, determine:

a. Total turbine work (kJ/kg).
b. Heat transfer for the reheat process (kJ/kg).
c. Thermal efficiency of the cycle.