how do you find the cost per unit of cost of goods sold? it said $16 was wrong.

The following are the transactions for the month of July Unit Selling Price Unit Cost $10 12 July 1 July 13 July 25 July 31 Units 44 220 (100) 164 Beginning Inventory Purchase Sold Ending Inventory $16 M7-9 Calculating Cost of Goods Available for Sale, Ending Inventory, Sales, Cost of Goods Sold, and Gross Profit under Periodic Weighted Average Cost [LO 7-3] Calculate cost of goods available for sale and ending inventory, then sales, cost of goods sold, and gross profit, under weighted average cost. Assume a periodic inventory system is used (Round "Cost per Unit" to 2 decimal places and your final answers to nearest whole dollar amount.) Weighted Average (Periodic) Cost per Units Total Unit 441 $ 10.00 s 440 220 $ 12.00 2640 3,080 Beginning Inventory Purchases Goods Available for Sale Cost of Goods Sold Ending Inventory 100 0