I really like this activity because of the real life application of choosing the best payment option. I have found when students hear this type of activity it really captures their attention. I think they will really like this activity. I plan to work on this activity this week because we are working on linear functions and slope right now. I agree that they may have some trouble with the larger numbers but a review on scale and how to set up a graph will lead to great discussion. Thanks for sharing this lesson on the three types of payment plans. I have never seen this problem before.