A machine with a cost of $65,000 has an estimated residual value of $5,000 and an estimated life of 5 years or 15,000 hours. it is to be depreciated by the units-of-production method. what is the amount of depreciation for the second full year, during which the machine was used 5,000 hours? $8,000 $12,000 $20,000 $21,667