48/2(9+3) = 48/2*(9+3) = 48*(1/2)*(9+3) = 288
48/2(9+3) != 48*(1/(2(9+3)) because that involves, once again, parentheses around 2(9+3) which does not exist. And, no you cannot insert or imply parentheses in that case, because it trumps multiplication in the order of pemdas.
Same arguments...