Requir information [The following information applies to the questions displayed below.] Trey Monson starts a merchandising business on December 1 and enters into the following three inventory purchases. Monson uses a periodic inventory system. Also, on December 15. Monson sells 15 units for $20 each. Purchases on December 7 Purchasies on December 14 Purchases on December 21 10 units o $6 cost 20 units $12 cost 15 units $14 cost Determine the cosis assigned to ending inventory when costs are assigned based on the LIFO method