Kara followed these steps to evaluate the expression 22 + (30 - 4)-2. 30 - 4 = 26
26 + 22 = 48
48 - 2 = 24
George looks at Kara's work and says she made a mistake. He says
she should have divided by 2 before she added.
Which student is correct? Explain how you know.

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.