An electrician charges a base fee of $60 plus $40 for each hour of work. The minimum the electrician charges is $140. Create a table that shows the amount the electrician charges for 1, 2, 3, and 4 hours of work. Determine the domain and range of the relation in context and explain whether or not this represents a function.

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.