On the number line, you draw a closed/filled dot on 15. Then you draw a line from 15 all the way to 0. You can't pass 0 because you can't buy a negative amount of food items.
<u>For 5.</u>
The solution, x ≤ 15, means that Aiden can by at least 15 food items and a best gas grill and not go over his budget of $100.