b) Explain how to use the mathematical model to predict how many Americans will not have heakth insurance in 2021. Describe one event that could occur in the future that would make this prediction highly inaccurate.

Set $r$ is a set of rectangles such that (1) only the grid points shown here are used as vertices, (2) all sides are vertical or horizontal and (3) no two rectangles in the set are congruent. if $r$ contains the maximum possible number of rectangles given these conditions, what fraction of the rectangles in set $r$ are squares? express your answer as a common fraction.