The Drunken Lizard Pub

OK, So I finally got into Astral Range and I opened a can of Whoop-Ass on Alunder and killed him. It was easier to kill him than even cockroaches. Rather anti-climatic after all the hype about him. Anywho, now I'm down in the dungeon and I've hit all the switches on the "second" side, but nothing else is opening up. And I've gotten the pass out of the chest for the gate to the north and there is nothing up there but "Turn around!" What am I missing, here? It seems there was more difficulty getting here.

You need be in the dungeon.

[+] SPOILER

Add the numbers shown in each of the painting in the north for the first gate, and for the second gate, subtract all the numbers in the southern side from the total of the numbers in the northern side.