Carlos uses a food delivery service to order lunch. He paid $13.75 for lunch, which included the cost of the food and a delivery fee, which is 10% of cost of the food. What was the cost of Carlos' lunch before the delivery fee? Enter your answer in the box.

$12.50

Step-by-step explanation:

Let x = the cost of the food without the delivery fee.

The delivery fee can be represented as 0.10x.

Keep in mind that the cost of the food plus the delivery fee equals $13.75.

Therefore, your equation will look like: 13.75 = x + 0.10x

x + 0.1x = 1.10x

So, 13.75 = 1.10x

This means that x = 13.75/1.10

x = 12.5 = $12.50

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