Equipment was acquired on January 1, 2017 at a cost of $78,000. The equipment was originally estimated to have a salvage value of $5,210 and an estimated life of 10 years. Depreciation has been recorded through December 31, 2020 using the straight-line method. On January 1, 2021, the estimated salvage value was revised to $7,020 and the useful life was revised to a total of 8 years. Determine the depreciation expense for 2021.