Calculate the book value of a three-year old machine that has a cost of $ 26.000, an estimated residual value of $ 1.000, and an estimated useful life of 50.000 machine hours. The company uses units-of-production depreciation and ran the machine 3.200 hours in year 1; 7.050 hours in year 2; and 7.500 hours in year 3. Answer: NBV at the end of the third year is $