... Opening stock $ - $3, 120 Stock purchases $34 ,32 0 $49,920 Less closing stock $3, 120 $6,240 Total cost of goods sold(COGS) $31 ,200 $46,800 Gross Profit $20,800 $31 ,200 Expenses ... @ 31 .20 each) Equals stock available to sell $34 ,32 0 Less stock on hand at end of year $3, 120 (100 tyres @ 31 .20 each) Cost of goods sold $31 ,200 If your business is a service business, ... Cost of goods sold Opening stock $ - Stock purchases $34 ,32 0 Less closing stock $3, 120 Total cost of goods sold (COGS) $31 ,200 (See note below) Gross profit $20,800 ...