South Airlines purchased a 747 aircraft ox January 1,2017, at a cost of $35,000,000. The estimated useful lifn 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 15 years with a revised salvage value of $3,500,000.

1) Compute the depreciation and book value at December 31,2019 using the straight-line method and the double-declining-balance method.

2) Assuming the straight-line method is used, compuve the depreciation expense for the year ended December 31,2020.