how to do this?

Bill owns a data processing company. He plans to buy an additional computer for $20,000, use the computer for 3 years, and sell it for $10,000. He expects that the use of the computer will produce a net income of $8,000 per year. The combined federal and state tax rate is 45%. Using MACRS depreciation, complete the table below to determine the net present worth of the after-tax cash flow using an interest rate of 12%