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.

Question

What was the cost of Carlos' lunch before the delivery fee?

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$

Answer 1

Let the cost of the food before the delivery fee be denoted as \( x \). The delivery fee is 10% of the cost of the food, which can be expressed mathematically as \( 0.10x \).

The total cost Carlos paid for lunch, which includes both the food and the delivery fee, is given by:

\[ x + 0.10x = 13.75 \]

Combining the terms, we have:

\[ 1.10x = 13.75 \]

To find \( x \), we divide both sides by 1.10:

\[ x = \frac{13.75}{1.10} \]

Now, let's calculate that:

\[ x = 12.50 \]

Thus, the cost of Carlos' lunch before the delivery fee was

\[ \boxed{12.50} \]