Marie was trying to show her friend why -3 × -8 equals a positive product. this is what she wrote: -3 × 0 = 0 -3 × = 0 -3(8) + -3(-8) = 0 -24 + 24 = 0 what should marie write in place of the question mark? a. 8 + 8 b. -8 + (-8) c. 8 + (-8) d. -8 + 0

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.