The area of square park is 400 square metre calculate the length of the side of the park

Find x to the nearest hundredth place

Prove that quadrilateral is a rhombus.

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.