In response to complaints about high prices, a grocery chain runs the following advertising campaign: If you pay your child $8 to go buy $100 worth of groceries, then your child makes twice as much on the trip as we do. Youve collected the following information from the grocery chains financial statements: (in millions) Sales $ 600.0 Net income 24.0 Total assets 330.0 Total debt 200.0 a. What is the profit margin for the child as a percentage of what they spend and the profit margin for the store? (Do not round intermediate calculations and enter your answers as a percent rounded to 2 decimal places, e.g., 32.16.) b. What is the store's ROE? (Do not round intermediate calculations and enter your answer as a percent rounded to 2 decimal places, e.g., 32.16.)