The following information is taken from the records of four different companies in the same in- dustry: A B D Sales $300 $150 $ ? $ 90 Opening Inventory ? 40 40 12 Purchases 240 ? ? 63 Cost of Goods Available for Sale 320 ? 190 ? Ending Inventory ? (60) (60) (15) Cost of Goods Sold ? 100 130 60 Gross Profit $100 ? $ 65 $ ? Gross Profit percentage ? ? ? ? $ ? $ Required: a. Calculate the missing amounts. b. Which company seems to be performing best? Why