Required 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 perpetual inventory system. Also, on December 15 , Monson sells 15 units for $21 each. If the units sold, 8 are from the December 7 purchase and 7 are from the December 14 purchase. Determine the costs assigned to nding inventory when costs are assigned based on specific identification