A new Community Sports Complex is being built in Madision. The perimeter of the rectangular playing field is 324 yards The length of the field is 6 yards less than double the width What are the dimensions of the playing field?

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.