(13). Hilal Company purchased a new machine on May 1, 2020, at a cost of $90,000. The company estimated that the machine has a salvage value of $18,000. The machine is expected to be used for 72,000 working hours during its 8-year life. Instructions Compute the depreciation expense under the following methods for the year indicated. (a). Straight-line for 2020. (0.4 mark) (b). Units-of-activity for 2020, assuming machine usage was 6,750 hours. (0.35 mark) (c). Sum-of-the-years' -digits method for 2021 (1 mark) (d). Declining-balance using double the straight-line rate for 2020 and 2021. (0.75 marks)