Hayat Company purchased equipment for $80,000 on January 1, 2019. Straight-line depreciation is used, based on a 5-year life and a $10,000 salvage value. In 2021, the estimates are revised. Hayat now feels the equipment will be used until December 31, 2022, when it can be sold for $5,000. The book value of equipment on 31/12/2020 is: O a $80,000. O b. $66,000 Oc$28,000 O d. $52,000