The key club is selling nachos at the football game to raise money for the club's activities. the club received good prices for the ingredients from the local stores, so each serving of nachos costs them only $0.50. the members plan to sell each serving of nachos for $1.25. what percent markup is in this price?

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.