10 points - 5 each) saudi royal airlines purchased a 747 aircraft on january 1, 2013, 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, 2016 the airline revises the total estimated useful life to 15 years with a revised salvage value of $3,500,000. instructions (a) compute the depreciation and book value at december 31, 2015 using the straight-line method. (b) using the straight-line method, compute the revised depreciation expense for the year ended december 31, 2016.