Find the missing term.
... 14,_. 15,-..
0.5
1
14.5
29

How do you do this geometry problem

If an athlete can bike 6 miles in 25 minutes, how many miles will he bike in an hour and half if he continues to bike at the same rate?

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.