A machine with a cost of $120,000 has an estimated residual value of $15,000 and an estimated life of 5 years or 15,000 hours. It is to be depreciated by the units-of-output method. What is the amount of depreciation for the second full year, during which the machine was used 5,000 hours? $5.000 O $35,000 O $21,000 O $45,000