Danielle is engineering a new brand of shoes, For shoes sold,
in thousands, a profit of pbx)=-3x4 + 4. -12 + 5x + 10
dollars, in ten thousands, will be earned.
a. How much will be earned in profit for selling 1,000 shoes?
b. What do the x-and y-intercepts of the graph mean in this
context? Do those values make sense?

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.