#### Answer

$x\le-9$

#### Work Step by Step

$\bf{\text{Solution Outline:}}$
Use the properties of inequality to solve the given inequality, $
3-x\ge12
.$
$\bf{\text{Solution Details:}}$
Using the properties of inequality, the given is equivalent to
\begin{array}{l}\require{cancel}
3-x\ge12
\\\\
-x\ge12-3
\\\\
-x\ge9
.\end{array}
Dividing both sides by a negative number (and consequently reversing the inequality symbol), the inequality above is equivalent to
\begin{array}{l}\require{cancel}
-x\ge9
\\\\
x\le\dfrac{9}{-1}
\\\\
x\le-9
.\end{array}