Clarence lives in maine, which has a sales tax of 5%. he just bought a digital camera whose full price was $725, but after sending in a rebate form, he later received a check in the mail for $125. what is the total amount that clarence ended up paying after receiving the rebate

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.