Michelle earned $150 during the summer for babysitting. she bought 2 packs of blu-ray disks worth $65 each using her babysitting money. how much money was left after she bought the blu-ray disks?

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.