pls explain step by step

Question 5. (20 pts) Suppose a utility company is selling electric power for $0.06/kW-h at night and is willing to pay $0.13/kW-h fo/ oower produced during the day. To take advantage of this opportunity, an entrepreneur is considering boilding a large reservoir 50m above the lake level, pumping water from the lake to the reservoir at night using cheap power, and letting the water flow from the reservoir back to the lake during the day, producing power as the pump-motor operates as a turbine-generator during reverse flow. Preliminary analysis shows that a water flow rate of 2m3/s can be used in either direction, and the irreversible head loss of the piping system is 4m. The combined pump-motor and turbine-generator efficiencies are expected to be 75% each. (a) (15 pts) Determine the electric power (in kW ) consumed by the pump-motor during the night and the electric power (in kW) produced by the turbine-generator during daytime. (b) (5 pts) Assume the system operates for 10h each in the pump and the turbine modes in a typical day. What is the expected revenue per year