Answer:
[tex]\large\boxed{n\leq9\ or\ n>13\to n\in\left(-\infty;\ 9\right]\ \cup\ (13,\ \infty)\to\{x\ |\ x\leq9\ or\ x>13\}}[/tex]
Step-by-step explanation:
[tex]n-12\leq-3\ or\ 2n>26\\\\n-12\leq-3\qquad\text{add 12 to both sides}\\n\leq9\\\\2n>26\qquad\text{divide both sides by 2}\\n>13\\\\n\leq9\ or\ n>13\to n\in\left(-\infty;\ 9\right]\ \cup\ (13,\ \infty)\to\{x\ |\ x\leq9\ or\ x>13\}[/tex]
