Ottawa Corporation owns machinery that cost $20,000 when purchased on July 1, 2014. Depreciation has been recorded at a rate of $2,400 per year, resulting in a balance in accumulated depreciation of $8,400 at December 31, 2017. The machinery is sold on September 1, 2018, for $10,500. Prepare journal entries to (a) update depreciation for 2018 and (b) record the sale.