The question is ambiguous. I don't want this thread to turn into (yet another) debate on the correct answer, but the answer should be 288.
48÷2(9+3)
=48÷2(12)
=24(12)
=288
As I said though, there should be more brackets to indicate exactly what should be going on, as although we do multiplication/division from left to right, it's not a law.