PW Corporation uses a periodic inventory system. At the end of 2019, the accounting records include the following information: Inventory, 31 December 2018 Inventory, 31 December 2019 Purchases Sales Sales Returns $15,000 $23,000 $220,000 $420,000 $20,000 Required: (a) Compute (i) the cost of goods sold; (ii) gross profit; and (iii) the gross profit rate (in %) for the year 2019. Show your workings. (6 marks) (b) Prepare two closing entries to create the Cost of Goods Sold account and update the Inventory account