NEED ANSWER ASAP PLEASE!!

For fiscal year 2015, Wal-Mart Stores, Inc. (WMT) had total revenues of $485.65 billion, net income of $16.36 billion, total assets of $203.49 billion, and total shareholders' equity of $81.39 billion.

a. Calculate Walmart's ROE directly, and using the DuPont Identity. The ROE calculated directly is what %? (Round to two decimal places.)

b. Comparing with the data for Costco below, use the DuPont Identity to understand the difference between the two firms' ROEs. What is the %?

Data Table:

For fiscal year 2015, Costco Wholesale Corporation (COST) had a net profit margin of 2.05%, asset turnover of 3.48, and a book equity multiplier of 3.15. Costco's ROE (DuPont) is 22.47%.