Five skid steers costing $20,000 each were purchased by the Biggs Excavating Company at the beginning of 2016. Biggs capitalized the skid steers in a single asset account and depreciates them using the group method. Each skid steer was expected to have a residual value of $6,000 in four years. At the end of 2019, Biggs sold one skid steer for $8,000. For what amount is accumulated depreciation debited in the journal entry to record the disposal of that skid steer?