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 $32 each. Purchases on December 7 Purchases on December 14 Purchases on December 21 10 units @ $18.00 cost 20 units @ $24.00 cost 15 units @ $26.00 cost QS 5-11 (Algo) Perpetual: Assigning costs with FIFO LO P1 Required: Determine the costs assigned to the December 31 ending inventory based on the FIFO method.