A vehicle with a cost of $34,000 has an estimated salvage value of $4,000 and an estimated life of 4 years or 150,000 miles.. It is to be depreciated using the units-of-activity method. What is the amount of accumulated depreciation at the end of the second full year if the car is driven 9,000 miles in the first year and 21,000 miles in the second year? $6,800 $4,200 $7,400 $6,000