Whippet Bus Lines uses the units-of-activity method in depreciating its buses. One bus was purchased on January 1, 2017, at a cost of $126,000. Over its 4-year useful life, the bus is expected to be driven 210,000 miles. Salvage value is expected to be $8,400. Compute the depreciation cost per unit. (Round answer to 3 decimal places, es, 6.251) Depreciation cost per units eTextbook and Media Prepare a depreciation schedule assuming actual mileage was: 2017, 50,400: 2018, 65,520:2019,51,660; and 2020, 34,020. (Round depreciation cost per unit to 3 decimal places, e.g. 0.125 and other answers to decimal places, eg. 125)