A cell phone plan is shown at the right. The rates, which include an unlimited data plan, are the same each month for 7 months. The total cost for all 7 months is 180.39. Let m represent the average number of minutes that exceeds 700 minutes each month

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.