Exercise 6-18 Perpetual inventory costing @ @ Tree Seedlings has the following current-year purchases and sales for its only product. Date Activities Units Acquired at Cost Units Sold at Retalt Jan. 1 Beginning inventory 4o units @ $2 - $ 80 Jan. 3 Sales 30 units 88 Purchase 70 units $3 - $210 Sales 60 units@ $8 June 30 Purchase go units of $4$300 Nov 6 Sales 86 units $8 Nov. 19 Purchase 20 units @ $5 $100 Totals 20 units $750 176 units Feb. 14 Feb. 15 Required The company uses a perpetual inventory system. Determine the costs assigned to ending inventory and to cost of goods sold using (a) FIFO and (b) LIFO. (c) Compute the gross margin for each method