Steam enters a turbine at 450 lbf/in 2, 900 F, expands in a reversible adiabatic process and

Question:

Steam enters a turbine at 450 lbf/in 2, 900 F, expands in a reversible adiabatic process and exhausts at 2 lbf/in.2. Changes in kinetic and potential energies between the inlet and the exit of the turbine are small. The power output of the turbine is 800 Btu/s. What is the mass flow rate of steam through the turbine?