Answer:
[tex]\large\boxed{a\geq7\to a\in[7,\ \infty)}[/tex]
Step-by-step explanation:
[tex]2a-3\geq11\qquad\text{add 3 to both sides}\\\\2a-3+3\geq11+3\\\\2a\geq14\qquad\text{divide both sides by 2}\\\\\dfrac{2a}{2}\geq\dfrac{14}{2}\\\\a\geq7[/tex]
