An industrial robot that is depreciated by the MACRS method has B = $60,000 and a 5-year depreciable life. If the depreciation charge in year 3 is $8640, the salvage value that was used in the depreciation calculation is closest to: (dt values for years 1, 2, 3, 4, and 5 are 10.00%, 18.009, 14.40%, 11.52%, and 9.22%, respectively.) (a) $0 (b) $10,000 (0) $20,000 (d) $30,000