Grace earns $7 for each car she washes. she always saves $25 of her weekly earnings. this week, she wants to have at least $65 in spending money. how many cars must she wash? write and solve the inequality to represent this situation. interpret the solution in context.

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.