Jim’s diner offers its clients a choice of regular and diet soda. Last night, the diner served 30 sodas in all, 30% of wich were regular. How many Regular sodas did the diner serve?

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.