Answer
$ c\leq 5$
The graph is shown below.
Work Step by Step
The given inequality is
$\Rightarrow -15\leq -3c$
Divide each side by $-3$. Reverse the inequality symbol.
$\Rightarrow \frac{-15}{-3}\geq \frac{-3c}{-3}$
Simplify.
$\Rightarrow 5\geq c$
Hence, the solution is $ c\leq 5$.
Use a close circle because $5$ is a solution.
Shade the number line on the left side.
