Why the question mark?
You'll have to ask z-man; he posted it that way.
Why not solve for "X"?
? * any n>0=X...ALWAYS! 
48÷2(12) = X
Doing the division first by canceling the 2 with the 48.
24÷1(12) = X
2 = X
Nope. 288 = X.
Like I said, I'll go along with the 288...
Great! I'm sure Al Gebra will breathe a sigh of relief! 
with the understanding that...
Uh, oh 
in school this would have been an extra credit question as the format is poor...
48÷2(9+3) = X is neither 'poor' nor 'excellent' nor any other subjective adjective one may choose to use...it simply is what it is, i.e.,'valid', or any of its synonyms.
and would not be tolerated as an answer or sample problem by an author of text books.
Then that unqualified author should be banned from writing textbooks! 
NO! He/she should be burned like a steak on a pile of any of his/her books that may have made it into circulation and then his/her ashes violently stomped into a mold to form a square pi!!
X=288
Seriously, just because 63% of those polled here stumble over their own math prowess and come up with the wrong answer isn't the fault of the equation. 
..