Final answer:
The cost of Jen's balloon orders is non-proportional because there is a fixed shipping cost of $2.79 in addition to the cost per balloon. The equation y = 0.99x + 2.79 indicates a non-proportional relationship due to the constant shipping cost.
Step-by-step explanation:
The question asks whether the cost of Jen's balloon orders is proportional or non-proportional. If it were proportional, the total cost would increase by the same rate for each additional balloon. However, since there is an additional fixed shipping cost of $2.79, regardless of the number of balloons ordered, the relationship between the number of balloons and the total cost is non-proportional.
To explain using an equation, let x be the number of balloons, and y be the total cost. Then the equation is y = 0.99x + 2.79. Because of the constant term 2.79, which represents the shipping cost, the relationship is not proportional. Without that term, the cost would increase by $0.99 for each balloon, which would be a direct variation, or proportional relationship.