PLEASE ANSWER IT ASAP I'LL UP VOTE THE ANSWER FOR A IS 12.9% FOR B the answer should be correct thank you

In the vapor-compession cycle a throttling device is used almost universally to reduce the pressure of the liquid refrigerant. a) Determine the percent saving in net work of the cycle per kilogram of refrigerant if an expansion engine could be used to expand saturated liguit refrigerant 22 isentropically from 35C to the evaporator temperature of 0C. Assume that compression is isentropic from saturated vapor at 0C to a condenser pressure corresponding to 35C. Ans. 12.9% b)Calculate the increase in refrigerating effect in kilojoules per kilogram resulting from use of the expansion engine