the answer is 8150, but I DONT UNDERSTAND HOW TO GET IT

Stanton Inc. is considering the purchase of a new machine which will reduce manufacturing costs by $5,000 annually and increase sales by $6,000 annually. Stanton will use the MACRS method to depreciate the machine, and it expects to sell the machine at the end of its 3-year operating life for $10,000 before taxes. Stanton's marginal tax rate is 40 percent, and it uses a 9 percent cost of capital to evaluate projects of this type. If the machine's cost is $20,000, what is the project's NPV? [Note: MACRS table required] ( 15 points)