User blog comment:A, Mori/Decalogue Pet Contest/@comment-3293097-20140210221018

Are you sure the riddle is solvable? I ended up at a dead end where:

TL = BR + 3

BL = BR - TL

TR = BL x 9001

BR = 12 - 9 = 3

BL = 3 - TL = 3 - BL + 3 = BL

TL = BL + 3 = 3 - TL + 3 = TL

The solvability ends where BL and TL can only be defined in terms of each other or themselves. Without being able to find a numerical value for BL, we cannot figure out TR.