Sheridan Co. purchased a machine on January 1, 2018, for $610,500. At that time, it was estimated that the machine would have a 10-year life and no salvage value. On December 31, 2021, the firm's accountant found that the entry for depreciation expense had been omitted in 2019. In addition, management has informed the accountant that the company plans to switch to straight-line depreciation, starting with the year 2021. At present, the company uses the sum-of-the-years'-digits method for depreciating equipment. Prepare the general journal entries that should be made at December 31, 2021, to record these events. (Ignore tax effects.) (Credit account titles are automatically indented when amount is entered. Do not indent manually. If no entry is required, select "No Entry" for the account titles and enter O for the amounts.) Date Account Titles and Explanation Debit Credit Dec. 31, 2021 (To correct for the omission of depreciation expense in 2019.) Dec. 31, 2021 (To record depreciation expense for 2021.)