A tractor for over-the-road hauling is purchased for $90,000.00. It is expected to be of use to the company for 6 years, after which it will be salvaged for $4,600.00. Calculate the depreciation deduction and the unrecovered investment during each year of the tractors life. a. Use straight-line depreciation. Provide depreciation and book value for year 6. Depreciation for year 6 = $ book value for year 6 = $ b. Use declining-balance depreciation, with a rate that ensures the book value equals the salvage value. Provide depreciation and book value for year 6. Depreciation for year 6 = $ book value for year 6 = $ c. Use double declining balance depreciation. Provide depreciation and book value for year 6. Depreciation for year 6 = $ book value for year 6 = $ d. Use double declining balance, switching to straight-line depreciation. Provide depreciation and book value for year 6. Depreciation for year 6 = $ book value for year 6 = $