Hi! I'm going to assume that your chart went something like 1 ride is 20 dollars, 2 rides are 60, and 3 rides are 40 dollars.
Proportional relationships are when the proportions between the two variables x and y are constant. Thinking of a chocolate being the same price per bar no matter how much you buy of it in bulk might help you out.
In this case, one ride is 20 dollars. However, if I were to buy two rides, it would be 30 dollars per ride. In the last ride, rides are 13.33 dollars for 3 rides. The price of each ride for each variable is different, therefore this would not be a proportional relationship.