Identify n in the equation below. then name the property that is used. 6=6+n -identity property of addition -identity property of addition -commutative property of addition -multiplicative property of zero

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.