Hi, can someone please guide me step by step, I don't understand how cost of goods are obtained and how to utilize these equations

BE6-6 Battery Limited uses a perpetual inventory system. The inventory records show the following data for its first month of operations: Date Explanation Units Unit Cost Total Cost Balance in Units Aug. 2 Purchases 250 $ 70 $ 17,500 250 3 Purchases 500 100 50,000 750 10 Sales (300) 450 15 Purchases 900 120 108,000 1,350 25 Sales (325) 1,025 Calculate the cost of goods sold and ending inventory using (a) FIFO and (b) average cost. (For average cost, use unrounded numbers in your calculations but round to the nearest cent for presentation purposes in your answer.)