A paper mill has two steam generators, one at 600 lbf/in 2, 550 F and one at 1250 lbf/in 2, 900 F. The setup is shown in Fig. P9.72. Each generator feeds a turbine, both of which have an exhaust pressure of 160 lbf/in.2 and isentropic efficiency of 87%, such that their combined power output is 20000 Btu/s. The two exhaust flows are mixed adiabatically to produce saturated vapor at 160 lbf/in 2. Find the two mass flow rates and the entropy produced in each turbine and in the mixing chamber.