We want to evaluate;
[tex]3+\lbrack-(-8)\rbrack[/tex]We can simply go about it like this,
[tex]\begin{gathered} 3+\lbrack-(-8)\rbrack \\ =3+\lbrack+8\rbrack\text{ since -}\times-=+ \\ =3+8 \\ =11 \end{gathered}[/tex]Therefore, the answer to the question is simply 11.
