The Assembly Department of​ Intuitive, Inc., manufacturer of​computers, had​ 4,500 units of beginning inventory in​ September, and​ 3,000 units were transferred to it by the Production Department. The Assembly Department completed​ 1,500 units during the month and transferred them to the Packaging Department. Calculate the total number of units accounted for by the Assembly Department if it had​ 6,000 units in ending inventory. The​weighted-average method is used.