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

$\text{Set Builder Notation: } \{ x|x\le12 \} \\\text{Interval Notation: } (\infty, 12]$
Using the properties of inequality, then \begin{array}{l}\require{cancel} x+3\le15 \\\\ x\le15-3 \\\\ x\le12 .\end{array} Hence, the solution set is \begin{array}{l}\require{cancel} \text{Set Builder Notation: } \{ x|x\le12 \} \\\text{Interval Notation: } (\infty, 12] .\end{array} In the graph, a hollowed dot is used for $\lt$ or $\gt.$ A solid dot is used for $\le$ or $\ge.$