Cool, fast and well done!
Also with sufficient proof of work (as far as I could decipher it, everything is absolutely correct, hehe)!
Maybe later I will add my envisaged solution (using Gaussian elimination) - but more urgent for you is surely to get your reward! :-) So to which account should I send the Dragon Whelp?
P. S.: Bist du Deutscher?
RE: Solve the mathematical puzzle and win a "Dragon Whelp", gold foil, 1 BCX! / Löse das mathematische Rätsel und gewinne einen "Dragon Whelp", Goldfolie, 1 BCX!