P4. The followings are inventory transactions of James Co. during May 2020. 5/1 Beginning inventory of 300 units at $10/unit 5/5 Bought 700 units at $11/unit. 5/10 Sold 400 units for $16/unit 5/15 Bought 600 units at $12/unit. 5/25 Sold 800 units for $16/unit. Instructions: Compute costs of goods sold and costs of ending inventory for May using the following methods under the periodic inventory system. 1. Average method. 2. First In First Out method. 3. Last in First Out method