[tex] \bf ~~~~~~~~~~~~\textit{middle point of 2 points }
\\\\
X(\stackrel{x_1}{-11}~,~\stackrel{y_1}{-6})\qquad
Y(\stackrel{x_2}{x}~,~\stackrel{y_2}{y})
\qquad
\left(\cfrac{ x_2 + x_1}{2}~~~ ,~~~ \cfrac{ y_2 + y_1}{2} \right)
\\\\\\
\left( \cfrac{x-11}{2}~~,~~\cfrac{y-6}{2} \right)=\stackrel{\stackrel{Midpoint}{M}}{(15,4)}\implies
\begin{cases}
\cfrac{x-11}{2}=15\\[0.8em]
x-11=30\\
\boxed{x=41}\\[-0.5em]
\hrulefill\\
\cfrac{y-6}{2}=4\\[0.8em]
y-6=8\\
\boxed{y=14}
\end{cases} [/tex]
[tex] \bf ~~~~~~~~~~~~\textit{middle point of 2 points }
\\\\
X(\stackrel{x_1}{x}~,~\stackrel{y_1}{y})\qquad
Y(\stackrel{x_2}{19}~,~\stackrel{y_2}{0})
\\\\\\
\left( \cfrac{19+x}{2}~~,~~\cfrac{0+y}{2} \right)=\stackrel{\stackrel{Midpoint}{M}}{(-4,8)}\implies
\begin{cases}
\cfrac{19+x}{2}=-4\\[0.8em]
19+x=-8\\
\boxed{x=-27}\\[-0.5em]
\hrulefill\\
\cfrac{0+y}{2}=8\\[0.8em]
\boxed{y=16}
\end{cases} [/tex]
