Exercise 5-18 Sustainability and perpetual inventory costing LO P1 Tree Seedlings has the following current-year purchases and sales for its only product. Units Sold at Retail Units Acquired at Cost 130 units @ $2 - $ 260 98 units @ $8 Date Activities Jan. 1 Beginning inventory Jan. 3 Sales Feb.14 Purchase Feb. 15 Sales June 30 Purchase Nov. 6 Sales Nov.19 Purchase Totals 192 units @ $3 - $ 576 180 units @ $4 - $ 720 150 units @ $8 140 units @ $8 56 units @ $5 - $ 280 558 units $1,836 388 units Required: The company uses a perpetual 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.