I got an answer already which is $56,443. But I need help with a cash flow diagram please. Thank you

11. (Chapter 5): A simple, direct space heating system is currently being used in a professional medical office complex. An upgraded "Variable air-volume system" retrofit can be purchased and installed for $200,000 (investment cost). Its power savings in the future will be 500,000 kilo-Watt hours per year over its estimated life of 8 years. The cost of electricity is $0.10 per kilo-Watt hour. If the firm's cost of capital is 12% per year and the residual value of the system in 8 years is $20,000 should the new system be purchased? Use the present worth method with cash flow diagram. (Points 20)