Need the LIFO and Gross Margin answers in the blue box. I have no idea where to find # of units sold under the "cost of goods sold" column. Please help and explain answers

[The following information applies to the questions displayed below.] Hemming Co. reported the following current-year purchases and sales for its only product. Date Activities Units Acquired at Cost Units sold at Retail Jan. 1 Beginning inventory 200 units @ $10 - $ 2,000 Jan. 10 Sales 150 units @ $40 Mar. 14 Purchase 350 units @ $15 5,250 Mar.15 Sales 300 units @ $40 July 30 Purehase 450 units @ $20 9,000 Oct. 5 Sales 430 units @ $40 Oct.26 Purchase 100 units @ $25 2,500 Totals 1,100 units $18,750 880 units Required: Hemming uses a periodic inventory system. (a) Determine the costs assigned to ending inventory and to cost of goods sold using FIFO. (b) Determine the costs assigned to ending inventory and to cost of goods sold using LIFO. (c) Compute the gross margin for each method. b) Periodic LIFO Cost of Goods Available for Sale Cost of Goods Sold Cost of Goods Cost per # of units # of units Available for Cost of unit sold unit Sale Goods Sold 200 $ 10.00 $ 2,000 50 $ 10.00 $ 500 Cost per Ending Inventory # of units Cost in ending Ending inventory per unit Inventory Beginning inventory Purchases: March 14 July 30 October 26 15.00 350 $ 450 $ 20.00 25.00 5,250 9,000 2,500 18,750 100 $ 1,100 Total $ 50 $ 500 0 $ 0 $ c) Gross Margin Sales Cost of goods sold Gross margin FIFO LIFO 35,200 $ 35,200 13,850 21,350 $