I am having trouble finding the standard form of an ellipse, being given the following equation:

I know that I have to group terms and complete the square to make it fit the standard form of an ellipse:

So I get to this and have been stuck:

I don't think I can just factor out the 12, and have

, so I tried factoring out the 36:

in which I got

<---which I got from

,which doesn't work out at all because I can't divide out what's to the right of the equal sign to get a nice looking equation that equals 1.

I'm completely baffled by this problem, so any help would be appreciated.