4 Gale Hawthorne Inc. purchased a new machine on September 1, 2018, at a cost of $548,000. The machine had an eight-year useful life and an estimated salvage value of $58,000. The company has a December 31" calendar year Instructions: (a) Compute the depreciation expense and the asset's net book value for 2018 and 2019 under the straight-line method (b) Compute the depreciation expense and the asset's net book value for 2018 and 2019 under the double declining balance method. (el Compute the depreciation expense and the asset's net book value for 2018 and 2019 under the sum-of-years-digit method