Depreciation on the company's equipment for 2017 is computed to be $13,000. the prepaid insurance account had a $6,000 debit balance at december 31, 2017, before adjusting for the costs of any expired coverage. an analysis of the company's insurance policies showed that $540 of unexpired insurance coverage remains. the office supplies account had a $420 debit balance on december 31, 2016; and $2,680 of office supplies were purchased during the year. the december 31, 2017, physical count showed $496 of supplies available. one-third of the work related to $15,000 of cash received in advance was performed this period. the prepaid insurance account had a $5,000 debit balance at december 31, 2017, before adjusting for the costs of any expired coverage. an analysis of insurance policies showed that $4,460 of coverage had expired. wage expenses of $3,000 have been incurred but are not paid as of december 31, 2017.