Kayla and Matt each improved their yards by planting grass sod and ornamental grass. They bought their supplies from the same store. Kayla spent $47 on 6 ft² of grass sod and 7 bunches of
ornamental grass. Matt spent $17 on 6 ft² of grass sod and 1 bunch of ornamental grass. What is
the cost of one ft² of grass sod and the cost of one bunch of ornamental grass?

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.