Need help please haha this is grueling lol

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 periodic inventory system. Also, on December 15, Monson sells 15 units for $20 each. f the units sold, eight are from the December 7 purchase and seven are from the December 14 purchase. Determine the costs signed to ending inventory when costs are assigned based on specific identification