Number 6 is incorrect. Remember when you see -(-1) that is addition because you are subtracting a negative from a negative so you take the negative sign away and you have a positive. The correct answer to 6 is -75. For number 9 the first thing that you are gonna do is distribute that negative sign to the -12 in parentheses. This will make it a positive 12 which leaves you with
-8+12-31=-27
Next for number 12 you will distribute the - sign onto the -9 in parentheses and the -16 in parentheses. This will leave you with -16+9+16=9
