Nash Co. purchased a equipment on January 1, 2015, for $583,000. At that time, it was estimated that the equipment would have a 10-year life and no salvage value. On December 31, 2018, the firms accountant found that the entry for depreciation expense had been omitted in 2016. In addition, management has informed the accountant that the company plans to switch to straight-line depreciation, starting with the year 2018. 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, 2018, to record these events. (Ignore tax effects.)