Rectangle A'B'C'D' is the image of rectangle ABCD after a dilation centered at point P. What scale factor was used in the dilation?

Enter your answer as a simplified fraction in the box

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.