Angstrom Corporation purchased a truck at a cost of $60,000. It has an estimated useful life of five years and estimated residual value of $5,000. At the beginning of year three, Angstrom's managers concluded that the total useful life would be four years, rather than five. There was no change in the estimated residual value. What is the amount of amortization that Angstrom should record for year 3 under the straight-line method?