Martinez Company purchased a computer system for $72,500 on January 1, 2019. It was depreciated based on a 7-year life and an $17,200 salvage value. On January 1, 2021, Martinez revised these estimates to a total useful life of 4 years and a salvage value of $10,200. Martinez uses straight-line depreciation. Prepare Martinez's entry to record 2021 depreciation expense. (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.) Account Titles and Explanation Debit Credit