Two stage compressor with intercooling between the stages is used to compress air from 1 bar and 15c to 9 bar in a gas-turbine cycle . the high pressure turbine drives the compressor whereas low pressure turbine is coupled with an electrical generator. the compressor and turbine efficiencies are 85%; 75%, respectively. heat is added to the compressed air after leaving the compressor till its temperature reaches 900c. the air then expands in hpt to an intermediate pressure and reheat to the 900c before expanding another time in lpt to 1 bar. find the intermediate pressure, the turbine work, the back work ratio, and the cycle thermal efficiency. assume 15 kg/s air flow rate.