A table of the values for the exponential function f is shown below. The values represent the value of the car over a period of 5 years since it was purchased. Use an expoential regression to determine a function for this data. Table > (0,25500) ( 1,21675) (2,18424) (3,15660) (4,13311) (5,11314)

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.