billion, and net income of $5.01 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 2021 ? a. Compare the gross margins for Walmart and Costco. The gross margin for Walmart is The gross margin for Costco is b. Compare the net profit margins for Walmart and Costco. The net profit margin for Walmart is The net profit margin for Costco is \%. (Round to two decimal places.) \%. (Round to two decimal places.) c. Which firm was more profitable in 2021? (Select from the drop-down menu.) (1) was more profitable in 2021. (1) Costco