Question:
Point $A$ lies somewhere within or on the square which has opposite corners at $(0,0)$ and $(2,2)$. Point $B$ lies somewhere within or on the square which has opposite corners at points $(4,2)$ and $(5,3)$. What is the greatest possible value of the slope of the line containing points $A$ and $B$? Express your answer as a common fraction.

Answer:
Since point $A$ is constrained to a rectangular region with sides parallel to the axes, its $x$ and $y$ coordinates can be chosen independently of one another.  The same is true of point $B$.  Therefore, the horizontal separation between $A$ and $B$ should be minimized and the vertical separation maximized.  The greatest possible $y$-coordinate for $B$ is 3 and the least possible $y$-coordinate for $A$ is 0.  The greatest possible $x$-coordinate for $A$ is 2 and the least possible $x$-coordinate for $B$ is 4. Therefore, the slope between $A$ and $B$ is maximized when $A$ has coordinates (2,0) and $B$ has coordinates (4,3).  The maximum slope is $\boxed{\frac{3}{2}}$.