On January 1, 2018, the Excel Delivery Company purchased a delivery van for $51,000. At the end of its five-year service life, it is estimated that the van will be worth $4,200. During the five-year period, the company expects to drive the van 100,000 miles. Required: Calculate annual depreciation for the five-year life of the van using each of the following methods. 2. Sum-of-the-years-digits.