You (many years ago) are deciding whether to upgrade your company's equipment from typewriters to computer technology at a cost of $2,500 per machine, and machines will be replaced one-to-one. The typewriter technology was able to output $8,000 per unit per year, and you expect the computers to be able to output $8859 per unit per year (forever), but render the typewriters completely worthless. What would the NPV be of making this upgrade, per upgraded unit? Assume a 9.9% interest rate. Show calculation in 4 decimal places.