Elliot got some new trading cards. He has 4 packs with 20 cards each. Another pack has only 8 cards. Which equation shows a way to find how many cards Elliot has in all?
c = (4 x 20) + 8
c = 4 + 20 + 8
c = (4 x 8) + 20

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.