[tex] \bf ~~~~~~~~~~~~\textit{middle point of 2 points }
\\\\
(\stackrel{x_1}{x}~,~\stackrel{y_1}{y})\qquad
(\stackrel{x_2}{0}~,~\stackrel{y_2}{-11})
\qquad
\left(\cfrac{ x_2 + x_1}{2}~~~ ,~~~ \cfrac{ y_2 + y_1}{2} \right)
\\\\\\
\left( \cfrac{0+x}{2}~~,~~\cfrac{-11+y}{2} \right)~~=~~\stackrel{midpoint}{(-6,-14)}\implies
\begin{cases}
\cfrac{0+x}{2}=-6\\[0.8em]
0+x=-12\\
\boxed{x=-12}\\[-0.5em]
\hrulefill\\
\cfrac{-11+y}{2}=-14\\[0.8em]
-11+y=-28\\
\boxed{y=-17}
\end{cases} [/tex]
