Ben is making a dessert that requires 2.5 pound of strawberries and 1.5 pounds of blueberries. the straw berries cost $1 less per pound. ben paid a total of $9.50 on the fruit what was the price per pound of each fruit?

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.