Nice use of brackets. We know exactly what you mean.
(10 - 7 + 2) / (-2 + 1) Notice that with an even number of - signs, you get a plus and with and odd number you get a minus.
(5) / (-1) = - 5 answer
Edit
Numerator
10 does not change.
+ - 7 Here a plus and a minus are put together. There is 1 minus sign which is an odd number of minus signs so the 7 is minus
- - 2 Here there are 2 minus signs. They become plus because 2 is even, and an even number of minuses become a plus so you have +2
10 - 7 + 2 = 5
Denominator
-2 does not change. It remains minus 2.
- - 1 There are 2 minus signs so this becomes plus 1.
- 2 + 1 = - 1
Numerator over denominator = 5/-1 = - 5. I'll probably run out of editing time. If you still don't understand, try and pinpoint the problem and we'll keep trying until you do see it. This question is worth it.