Instead of shares, primecoin does chains to calculate how much you get.
7 chains have more "shares" and a 6 chain.
So let's say 6 chains is 1 share.
7 chares are 2 shares.
If you hit 3 of each:
6 chain: 1 "share"x3 = 3
7 chain: 2 "share"x3 = 6
It does a calculation roughly like that.
Or you can go to the XPM wallet.
Go to the Console and "setgenerate true 2" (because 2 cores)
It should show your chainsperday in there.
http://anty.info/primecoin-calculator/Then go there and you'll figure it out. G'luck.