20. A pump station has an initial cost of $47,000. Other costs are: 1. Pumps: $9000 $4000 2. Control panel: 3. Annual maintenance: $550 4. Salvage value: 5. Discount rate: $10,000 8% Pump life is 10 years, control panel life is 20 years. Calculate the present worth PW of the pump station after 20 years. [Annualize the operating costs for 20 years ($5400). Calculate the cost of pump replacement after 10 years. ($4170). Calculate the value of salvage. (-$2145). PW-the sum.]