The cost of equipment purchased by Kingbird, Inc., on June 1, 2020, is $92,400. It is estimated that the machine will have a $8,400 salvage value at the end of its service life. Its service life is estimated at 7 years, its total working hours are estimated at 42,000, and its total production is estimated at 560,000 units. During 2020, the machine was operated 7,320 hours and produced 67,100 units. During 2021, the machine was operated 6,710 hours and produced 58,600 units. Compute depreciation expense on the machine for the year ending December 31, 2020, and the year ending December 31, 2021, using the following methods.

2020 2021 (a) Straight-line (b) Units-of-output (c) Working hours (d) Sum-of-the-years'-digits 0 (e) Double-declining-balance (twice the straight-line rate) $