How do I calculate less Accumulated Depreciation here?

On January 2, 2017, Favorite Clothing Consignments purchased showroorr fixtures for $12,000 cash, expecting the fixtures to remain in service for five years. Favorite has depreciated the fixtures on a double-declining-balance basis, with zero residual value. On October 31, 2018, Favorite sold the fixtures for S6,200 cash. Record both depreciation expense for 2018 and sale of the fixtures on October 31, 2018. (Record debits first, then credits. Select the explanation on the last line of the joumal entry table. Note that 2017 depreciation was recorded and posted in 2017.) Debit Credit Begin by recording the depreciation expense for January 1, 2018 through October 31, 2018 Date Accounts and Explanation Oct. 31 Depreciation Expense-Fixtures Accumulated Depreciation Fixtures 2,400 2,400 To record depreciation on fixtures. Before recording the sale of the fixtures, let's calculate any gain or loss on the sale of the fixtures. $ 6,200 Market value of assets received Less: Book value of asset disposed of Cost Less: Accumulated Depreciation $ 12,000 Gain or (Loss) Enter any number in the edit fields and then click Check