[kwstas]

I'm not really good at parsing information over text so I had to lay your solution out over the problem to get it.

https://i.imgur.com/OekI7jZ.png

> Note now that the stacked rectangles have the same horizontal width, and therefore must have the same vertical width.

This is the most important thing to use and what, were it included in the system in the OP, would simplify it quite a bit with not much more complexity. But the value of the approach I guess is the use of only pre-defined constraints.

Another route is to use that h_1 * (x+y) = 3A = 9 * (x+y) so h_1 = 9

[Tarq0n]

In the image the green square is actually less tall than the pink, which is really misleading.