As I posted earlier, there's a HUGE difference between 48 / 2 (9+3) and 48 / ((2(9+3)). You can't just make up where you put the "("s in. In this instance, I believe Agileguy is correct.
I understand people wanting to take the equation and make it ((48) x (1/24)), but I think we need to look at this equation as 48 x (1/2) x 12.
Granted it's been years since I was in college and while I don't have a degree, I did get 2 Advanced Calculus Credits from UConn. Kudos to Agileguy for a good one!