A system operating in a reversible cycle receives 25 kJ of heat at 225 C (1-2). This is followed by an adiabatic expansion
(2-3) to 115 C at which temperature 15 kJ of heat is received (3-4). Then a further adiabatic expansion (4-5) to 32 C occurs after which 25 kJ of heat is rejected at constant temperature (5-6) followed by an adiabatic compression (6-7). Find the change in entropy during the last process (7-1) which occurs after adiabatic compressions (6-7) to 115 C.