Concord Company purchased machinery on January 1, 2020, for $84,000. The machinery is estimated to have a salvage value of $8,400 after a useful life of 8 years. (a) Your answer is correct. Compute 2020 depreciation expense using the double-declining-balance method. Depreciation expense $ 21000 e Textbook and Media Assistance Used Attempts: 2 of 3 used (b) Compute 2020 depreciation expense using the double-declining-balance method, assuming the machinery was purchased on October 1, 2020. (Round answer to 0 decimal places, e.g. 5,125.) Depreciation exp $