You need 1.3 g of calcium per day. you get 290 mg of calcium per glass of milk. if you drink 4 glasses of milk, how much more calcium do you need from other sources?

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.