Answer
$\text{Set Builder Notation: }
\left\{ n|n\ge-8 \right\}
\\\text{Interval Notation: }
\left[ -8,\infty \right)$
Work Step by Step
Multiplying both sides by a negative number (and consequently reversing the inequality symbol), then
\begin{array}{l}\require{cancel}
-\dfrac{1}{2}n\le4
\\\\
-2\left(-\dfrac{1}{2}n\right)\le-2(4)
\\\\
n\ge-8
.\end{array}
Hence, the solution set is
\begin{array}{l}\require{cancel}
\text{Set Builder Notation: }
\left\{ n|n\ge-8 \right\}
\\\text{Interval Notation: }
\left[ -8,\infty \right)
.\end{array}
In the graph, a hollowed dot is used for $\lt$ or $\gt.$ A solid dot is used for $\le$ or $\ge.$
