1. Northeast Airlines purchased an aircraft on January 1,2022 , at a cost of $45,000,000. The e stimated useful life of the aircraft is 20 years, with an estimated residual value of $5,000,000. On January 1,2025 the airline revises the total estimated useful life to 13 years with a revised r esidual value of $4,000,000. Answer the following questions: (a) Compute the depreciation expense and book value of aircraft at December 31, 2024 using the straight-line method. (b) Assuming the straight-line method is used, compute the depreciation expense for the year ended December 31, 2025