Well, that's incorrect because according to the Order of Operation [GEMS\BOMDAS\PEMDAS etc.], that -7 has to be distributed amongst all the other terms in parentheses. Besides, you did the wrong operation when you inserted that subtraction symbol in substitution of the parentheses, which means to MULTIPLY. So, the order goes as follows:
12 - 7[72]
-504 + 12 = -492 [OR 12 - 504]
-492 is your answer. You get it now?