I underlined the part where you went wrong: 48/2(12) = 48/24

That is incorrect, because equation 48/2(12) is the same as 48/2*12 which means you:

1) divide

2) multiply

48/2=24

24*12 =288

the parenthesis must be eliminated before the division my friend.

I thought everyone learned this in the 6-7th grade?

The parenthesis in this case are only being used to denote multiplacation NOT being used as grouping symbols. The ONLY time you do parenthesis first is if there are OPERATIONS inside of them.

If you'd like this can be rewritten as

48/2*(9+3) = 48/2*12 = 24*12 = 288 = 24(12) = 48/2(12) = 48/2(9+3)

ALSO

48/2(9+3) = 288

48/[2(9+3)] = 2

There is a HUGE difference between these two equations. They are not equal and thus give two different answers. It's not that hard.