How many rectangles can be made from 12 boxes......
Also how many rectangles can be made fro 15 or 11 boxes.
Not enough information, thus an infinite number.
Now, each box has six faces which are rectangles themselves. This gives you a total of 72 rectangles. Are we putting these boxes together to make rectangular shapes? If so, then there are
$\displaystyle 12\choose1$ + $\displaystyle 12\choose2$ + $\displaystyle 12\choose3$ + ....$\displaystyle 12\choose12$ possibilities.