Can someone explain how to solve this problem? I am very confused on what to do. A = {3, 4, 7}

B = {1, 2, 5, 8}

U = {0,1,2,3...10}

Find the set:
(A n B) U (A n B')
within the universal set

(A intersect B) union (A intersect compliment B)

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.