Again, a simple fix is all this will take but it is frustrating. Why a textbook doesn't clearly point out where you divide and where you substract instead of divide is beyond mysterious. Also, I'm working a little ahead of the class right now so no access to the professor.

So here goes:

Solving for x; Ax+By=c

What I did was divideByby itself to getcoverBy. This leavesAx= c over By. Then I subtractedAfrom itself to get a final answer ofx=c over By -A.

But that's incorrect. Apparently I should have subtractedByfrom itself to getc-By. Then dividedAby itself for a final answer ofc-By over A

So what's the rule about when you subtract and when you divide? I have chemistry coming up in the fall so I'm especially keen to get this right. And of course I'll reiterate my current disdain for math textbooks leaving out simple but very key information.

Thank you in advance for your help.