Molly's Mobile Pet Grooming Service recently purchased a cargo van for $26,700. For depreciation purposes, the van is expected to have a useful life of 4 years and have a trade-in value of $4500. Molly uses the sum-of-the-years'-digits method to calculate depreciation. What is the book value at the end of the first year? $ What is the accumulated depreciation by the end of the second year? $ What is the annual depreciation in the third year?