South Airlines purchased a 747 aircraft on January 1, 2017, at a cost of $35,000,000. The estimated useful life of the aircraft is 20 years, with an estimated salvage value of $5,000,000. On January 1, 2020 the airline revises the total estimated useful life to 15 years with a revised salvage value of $3,500,000. (a) Compute the depreciation and book value at December 31, 2019 using the straight-line method and the double-declining-balance method. Accumulated depreciation Book value Straight-line Declining-balance