A Carnot heat engine using 1 kg of air has the following conditions: isothermal heat addition beginning at 15 MPa and 1200 K and continuing until the pressure is 10 MPa; adiabatic compression from 5 MPa and 500 K, continuing until the pressure is 15 MPa. Determine a) the heat transfer into the cycle; b) the heat transfer from the cycle; c) the work for each of the processes; d) the cycle thermal efficiency.