Hi there! So Andy's total lunch bill was $20 and the drink was 15% of the bill. Percents are parts of 100 and 100 - 15 is 85. That means 85% of the total bill was Andy's food cost. Let's multiply 20 by 85% ti get the cost of his food. 20 * 85% (0.85) is 17. Andy's food costed $17. Here are the answers broken down to be easier to read.
Percent of Andy's bill with food: 85%
Cost of food: $17