It all comes down to the strength of your cohort man. I'm averaging an A in both P.E and Business, so I should be getting the same study score right? Difference is I'm ranked 1 in P.E because the SACs were hard and my teacher doesn't give clues to students, so hard work pays off, where as in business I'm on the same grade but I'm ranked something like 6th-7th because teachers give out clues and answers to students.
But don't be fooled, people always say if you're ranked around 10th you're screwed, but that may be untrue because it varies depending on how your cohort performs.
Anyway, based on those grades you seem to be travelling along really nicely. It's actually impossible to predict your study scores from SAC grades, but you can easily get 40+ in all of your subjects. Don't make the mistake of thinking SAC scores are a clear indicator of your exam score, if you know your content really well, you should be able to score 40+
