Gotham Company purchased a new machine on October 1, 2017, at accost of $90,000. The company estimated that the machine has a salvage value of $8,000. The machine is expected to be used for 70,000 working hours during its 8-year life. Instructions: (Please, show all your work) Compute the depreciation expense under the straight-line method for 2017 and 2018, assuming a December 31 year-end. Compute the depreciation expense under the double declining-balance method for 2017 and 2018, assuming a December 31 year-end: Compute the depreciation expense under the units-of-activity method for 2017, assuming a December 31 year-end and that machine usage was 3, 900 hours