Elementary and Intermediate Algebra: Concepts & Applications (6th Edition)

$-12$
$\bf{\text{Solution Outline:}}$ Substitute $x=-12,$ to evaluate the given expression, $-(-x) .$ $\bf{\text{Solution Details:}}$ Substituting $x=-12,$ the given expression evaluates to \begin{array}{l}\require{cancel} -(-x) \\\\= -(-(-12)) \\\\= -(12) \\\\= -12 .\end{array}