6c -7 + 2 + 4 – 6d help plz

Simplify (a/b - b/a) times (a - a^2/a+b) a - a^2/a=b is a mixed number

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.

Tom travels between the two mile markers shown and then finds his average speed in miles per hour. select the three equations that represent this situation.