please answer these four part of the question. thank you

Marlow Company uses a perpetual inventory system. During the year, it entered into the following purchases and sales transactions. Units Sold at Retail Date Jan. 1 Feb. 10 Mar. 13 Mar. 15 Units Acquired at Cost 600 units @ $44/unit 400 units @ $40/unit 200 units @ $20/unit Activities Beginning inventory Purchase Purchase Sales Purchase Purchase Sales Totals 400 units $75/unit Aug. 21 Sep. 5 Sep. 10 160 units @ $60/unit 280 units @ $48/unit 200 units @ $75/unit 600 units 1.340 units Required 1. Compute cost of goods available for sale and the number of units available for sale. 2. Compute the number of units in ending inventory. 3. Compute the cost assigned to ending inventory using (a) FIFO. (b) specific identification-units sold consist of 500 units from beginning inventory and 100 units from the March 13 purchase, and (c) weighted average cost. (Round per unit costs to three decimals. but inventory balances to the dollar) 4. Compute gross profit earned by the company for cach of the three costing methods in part 3