Answer:
$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