On January 1, 2018 Time Stone Inc. purchased machinery for $45,000. The company estimated a useful life of 6 years and a $9,000 salvage value. On January 1, 2021, Time Stone revised the estimate of salvage value to $0 and determined the remaining useful life to be 2 years. If the company always uses the straight-line depreciation method, what is the balance in the accumulated depreciation account for the machinery as of December 31, 2021