Depreciation Methods A delivery truck costing $20,000 is expected to have a $2,000 salvage value at the end of its useful life of four years or 100,000 miles. Assume that the truck was purchased on January 2. Calculate the depreciation expense for the second year using each of the following depreciation methods: (a) straight-line, (b) double-declining balance, and (c) units-of-production. (Assume that the truck was driven 30,000 miles in the second year.)