Grouper Corp. purchased a piece of equipment for $42,000. It estimated a 8-year life and $1,680 salvage value. At the end of year 4 (before the depreciation adjustment), it estimated the new total life to be 10 years and the new salvage value to be $3,360. Compute the revised depreciation. Company uses straight-line depreciation method. (Round answer to decimal places, eg. 125.) Revised depreciation $