$11-2x < -9$
Move the constant to the right-hand side and change its sign$-2x < -9-11$
Calculate the difference$-2x < -20$
Divide both sides of the inequality by $-2$ and flip the inequality sign$\begin{align*}&x > 10 \\&\begin{array} { l }x \in \langle10, +\infty\rangle\end{array}\end{align*}$