or to make it real easy you can go on the cardas website and they have a program there where you just put in the width of your room and it'll give you the exact measurement from the front wall and the sidewall to put your speakers and I tried it and it works beautifully.
Question about speaker angle
I've always been under the impression that your front main speakers should be angled so that the "face" of the speaker is basically perpendicular with the listener's face when viewing the speakers from the sweet spot. I do however see others placing the speakers parallel or inline with the surface of the wall behind the speakers. I'm wondering, how much loss to the sonic sound stage this creates.