How can you use rates to determine whether a situation is a proportional relationship?

To determine if a situation is a proportional relationship, you can compare rates by calculating the ratio of two quantities. If the ratiOS remain constant across different pairs of values, the relationship is proportional. For example, if increasing the number of items consistently results in a proportional increase in total cost, the situation is proportional. Conversely, if the ratiOS change, the relationship is not proportional.