the donut stop acquired equipment for $27,000. the company uses straight-line depreciation and estimates a residual value of $5,000 and a four-year service life. at the end of the second year, the company estimates that the equipment will be useful for four additional years, for a total service life of six years rather than the original four. at the same time, the company also changed the estimated residual value to $2,800 from the original estimate of $5,000. required: calculate how much the donut stop should record each year for depreciation in years 3 to 6.