Answer: the equation is y = 4.5x - 15
Step-by-step explanation:
Let x represent the total number of sandwiches that shelly bought at her favorite restaurant.
Shelly has a gift card for her favorite restaurant for $15. Sandwiches cost $4.50 each. If she buys a total number of x sandwiches, it means that that the total cost will be 4.5×x = $4.5x
Let y represent the amount of money that she owes after buying x sandwiches. Therefore
y = 4.5x - 15