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Twenty-five percent of the customers entering a grocery store between 5 p.m. and 7 p.m. use an express checkout. consider five randomly selected customers, and let x denote the number among the five who use the express checkout.

Which one ? is the answer and how to find this answer

Your food costs are $5,500. your total food sales are $11,000. what percent of your food sales do the food costs represent?