On January 2, 2018, Archer Company, a skateboard manufacturer, installed a computerized machine in its factory at a cost of $168,000. The machine's useful life was estimated at four years or a total of 190,000 units with a $35,000 trade-in value. Archer Company's year-end is December 31. Calculate depreciation for each year of the machine's estimated useful life under each of the following methods: (Do not round intermediate calculations.) a. Straight-line b. Double-declining-balance c. Units-of-production, assuming actual units produced were: Year Units 2018 39,900 2019 43,550 2020 54,200 2021 72,000