the mathmatical equation is:
[Over locknut dimension - (cog to inside fork x 2)] / 2 = chainline for rear
Use order of operations. If you don't know order of operations, you shouldn't be trying to figure things like this out. Get your GED. knowledge is power!

Def start with the front. Unless your chainline is wicked off, it'll give you a good reference point to let you know if your math is somewhat correct.