In fiscal year 2018, Walmart Inc. (WMT) reported annual revenue of $514.41 billion, gross profit of $129.10 billion, and net income of $667 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.) The gross margin for Costco is \% (Round to two decimal places) b. Compare the net profit margins for Waimart and Costco The net profit margin for Walmart is % (Round to two decimal places.) The net profit margin for Costco is \%. (Round to two decimal places) c. Which firm was more profitable in 2018 ? (Select from the drop-down menu) was more profitable in 2018