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Treeline Co. uses a periodic system of inventory. The following information relates to the company's May inventory. Units Unit Cost Total Cost Beginning Inventory 100 $7 $ 700 May 10th purchase 200 $7 $ 1.400 May 20th purchase 300 $8 $ 2,400 Treeline sold 550 units in May, and it uses the average cost method to value inventory. What is the 5/31 onding inventory balance of Treeline's inventory? $ 350 $375, $367 $ 400