-8 -[2-(6-1)-7] = N
To answer this, first you must give your attention to the inner parenthesis (6-1)=5
-8-[2-5-7] = N In this case 5 is negative because we removed the parentesis.
-8+10=N since 10 is negative, removing the bracket will make it positive because negative times negative is positive.
So you will have