please explain why the useful life is like that aswell

iholletati P9-31A (book/static) Question Help On January 3, 2018, Rapid Delivery Service purchased a truck at a cost of $100,000. Before placing the truck in service, Rapid spent $3,000 painting it, $600 replacing tires, and $10,400 overhauling the engine. The truck should remain in service for five years and have a residual value of $12,000. The truck's annual mileage is expected to be 32,000 miles in each of the first four years and 8,000 miles in the fifth year-136,000 miles in total. In deciding which depreciation method to use, Andy Sargeant, the general manager, requests a depreciation schedule for each of the depreciation methods (straight-line, units-of-production, and double-declining-balance). Read the requirements, Requirement 1. Prepare a depreciation schedule for each depreciation method, showing asset cost, depreciation expense, accumulated depreciation, and asset book value. Accumulated Depreciation Book Value Begin by preparing a depreciation schedule using the straight-line method. Straight-Line Depreciation Schedule Depreciation for the Year Asset Depreciable Useful Depreciation Date Cost Cost S Life Expense 1-3-2018 114000 12-31-2018 102000 5 years = 20400 12-31-2019 81600/ 12-31-2020 12-31-2021 12-31-2022 On January 3, 2018, Rapid Delivery Service purchased a truck at a cost of $100,000. Before placing the truck in service, Rapid spent $3,000 painting it, $600 replacing tires, and $10,400 overhauling the engine. The truck should remain in service for five years and have a residual value of $12,000. The truck's annual mileage is expected to be 32,000 miles in each of the first four years and 8,000 miles in the fifth year-136,000 miles in total. In deciding which depreciation method to use, Andy Sargeant, the general manager, requests a depreciation schedule for each of the depreciation methods (straight-line, units-of-production, and double-declining-balance). Read the requirements. Requirement 1. Prepare a depreciation schedule for each depreciation method, showing asset cost, reciation expense, accumulated depreciation, and asset book value Begin by preparing a depreciation schedule using the straight-line method. Book Value Straight-Line Depreciation Schedule Depreciation for the Year Asset Depreciable Useful Depreciation Accumulated Date Cost Cost Life Expense Depreciation 1-3-2018 114000 12-31-2018 102000 5 years 20400 12-31-2019 81600/ 12-31-2020 12-31-2021 2 x (1/5) 12-31-2022 5 years 5 years x 2 136,000 miles Choose from any list or enter any number in the input fields and then click Check