In fiscal year 2018, Wal-Mart Stores (WMT) had revenue of $514.41 billion, gross profit of $129.10 billion, and net income of $6.67 billion. Costco Wholesale Corporation (COST) had revenue of $141.6 billion, gross profit of $18.42 billion, and net income of $3.13 billion. a. Compare the gross margins for Walmart and Costco. b. Compare the net profit margins for Walmart and Costco. c. Which firm was more profitable in 2018? a. Compare the gross margins for Walmart and Costco. The gross margin for Walmart is. (Round to two decimal places.)