Sean just purchased a new fish tank. he bought 7 guppies, 12 cichlids, 4 tetras, 9 corydoras and 2 synodontis catfishes.
1) what is the ratio of guppies to cichlids?
2) what is the ratio of tetras to catfishes?
3) what is the ratio of corydoras catfishes to the total number of fish?

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.