Billy Bob wants to consider purchasing a new fuel effieicnet furnance/air conditioner unit. The unit has been bid to cost $3198 to purchase and install. He estimates his annual savings to be $480 per year for the next 15 years. (Cost is at t=0, the savings can be considered annually beginning at t=1 and going until t=15), Billy considers opportunity cost of funds to be 6%. If he use the NPV method, what is the NPV he calculates for his project? (Assume annual compounding/discounting, and answer in $s to the nearest whole dollar without the $ sign needed, e.g,xxxx, or 1234)