Gary read 34 pages of a 340-page book. What percent did he read ?

How is working backward similar to solving an equation?

You are at a restaurant and owe $38 for your meal. you want to leave a 20% tip. how much will your tip be?

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.