Un January 1, 2019, the Mills Car Kepair Company acquired equipment at a cost of $65,000. At that time, the equipment was estimated to have a residual value of $3,000 at the end of an estimated five-year service life. During 2019 and 2020, the company recorded straight-line depreciation on the equipment. Required: Prepare all the joumal entries for 2021 relating to the equipment for each of the following independent situations (ignoring income taxes): a. Assume that the company switched to sum-of-the-years'-digits depreciation at the beginning of 2021 with a new estimated remaining life of four years. b. Assume, instead, that at the beginning of 2021 , the equipment is determined to have a five-year remaining service life. Straight-line depreciation will still be used. c. Assume, instead, that at the beginning of 2021 the company discovered that it had erroneously ignored the estimated residual value in the computation of its depreciation for 2019 and 2020