Bonita Corporation purchased a new machine for its assembly process on August 1,2020 . The cost of this machine was $139,200. The company estimated that the machine would have a salvage value of $21,300 at the end of its service life. Its life is estimated at 5 years, and its working hours are estimated at 22,500 hours. Year-end is December 31. Compute the depreciation expense under the following methods. Each of the following should be considered unrelated. (Round depreciation rate per hour to 2 decimal places, e.g. 5.35 for computational purposes. Round your answers to 0 decimal places, e.g. 45,892 .) (a) Straight-line depreciation for 2020 $ (b) Activity method for 2020 , assuming that machine usage was 800 hours $ (c) Sum-of-the-years'-digits for 2021 $ (d) Double-declining-balance for 2021 $