Final answer:
Marco would spend $26.25 on 5 bags of cat food, and this is not a proportional relationship.
Step-by-step explanation:
To determine how much Marco would spend on 5 bags of cat food, we first need to find the cost of 1 bag of cat food. Since 3 bags cost $15.75, we can divide the total cost by 3 to find the cost per bag: $15.75 / 3 = $5.25 per bag. To find how much Marco would spend on 5 bags, we multiply the cost per bag by the number of bags: $5.25 * 5 = $26.25. Therefore, Marco would spend $26.25 on 5 bags of cat food.
This is not a proportional relationship because the cost of the cat food does not remain the same as the number of bags increases. The cost increases as the number of bags increases.