A three-year-old machine has a cost of $61,000, an estimated residual value of $6,000, and an estimated useful life of five years. The company uses straight-line depreciation. Calculate the net book value at the end of the third year. Net book value A three-year-old machine has a cost of $25,000, an estimated residual value of $1,900, and an estimated useful life of 33,000 machine hours. The company uses units-of-production depreciation and ran the machine 5,100 hours in year 1; 7,550 hours in year 2; and 7,900 hours in year 3. Calculate the net book value at the end of the third year. Net book value