A three-year-old machine has a cost of $35,300, an estimated residual value of $2,300, and an estimated useful life of 33,000 machine hours. The company uses units-of-production depreciation and ran the machine 4,900 hours in year 1; 6,850 hours in year 2, and 8,300 hours in year 3. Calculate the net book value at the end of the third year. Net book value