What is 5? A prime Or composite?

Order the measurements from the least to the greatest. 2,720 ml , 24.91 l , 0.0268 kl

2x minus y equals 6, x plus y equals negative 3

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.