Trey Monson starts a merchandising business on December 1 and enters into the following three inventory purchases. Monson uses a perpetual inventory system. Also, on December 15 , Monson sells 28 units for $35 each. Purchases on December 718 units 8$14.00 cost Purchases on December 1433 units e $21.00 cost Purchases on Decenber 2128 units e $25.00 cost Important Notel Before you start working on this problem, watch the Hint video. This video shows you exactly how to work this problem. Required: Determine the costs assigned to the December 31 ending inventory based on the FIFO method