Machine x has an initial cost of $12,000 and annual maintenance of $700 per year. it has a useful life of four years and no salvage value at the end of that time. machine y costs $22,000 initially and has no maintenance costs during the first year. maintenance is $200 at the end of the second year and increases by $200 per year thereafter. machine y has a useful life of eight years and an anticipated salvage value of $5,000 at the end of its useful life. if the marr is 6%, what is the approximate net present worth (npw) of machine x?