You purchased an industrial oven five years ago for $70,000. O&M costs are $20,000 this year but are expected to increase by $1,500 each year for the next five years. The current salvage value of the machine is $20,000; salvage value after one year is estimated to be $10,000; after two years, $9,000; after three years, $8,000; after four years, $7,000; and so on. At i = 12%, find the remaining economic life of the asset.