they're all minus two, they're all minus two, so oxygen, each of these oxygens must have gained an electron, actually, let me rewrite this reaction, let me erase a little bit of it, so each of these, actually even better let me just move this over, much better, move that over there you go, and move that over, now let me fill in that so asthetically its pleasing, there you go, alright, so we have four oxygens witha zero oxidation state turning into four oxygens with a minus two oxidation state, so each of those four oxigens took two electrons, there's four of them, so we must have we must have gained eight electrons, so what happened to oxygen, its oxidation number went sown, or its hypothetical charge went down, it was reduced, its charge was reduced, reduced, ocygen was reduced, what was it reduced by?