39. A machine which cost $500,000 is acquired on October 1, 2020. Its estimated salvage value is $50,000 and its expected life is eight years. Required: Complete the form below by determining the depreciation expense and year-end book values for 2020 and 2021 by each of the following methods, showing the figures used. A. Straight-line method B. Double-declining balance C. Sum-of-the-years'-digits