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 15 units for $37 each. Parchases on Decenber? 10 units &$23.00 cost Purchases on Decenber 14 20 units 2$29+00 cost Purchases on December 2115 units $31.00 cost Required: Determine the costs assigned to the December 31 ending inventory based on the FIFO method