[tex]\bf ~~~~~~~~~~~~\textit{middle point of 2 points }\\\\
\begin{array}{ccccccccc}
&&x_1&&y_1&&x_2&&y_2\\
% (a,b)
&J&(~ 0 &,& 2~)
% (c,d)
&H&(~ x &,& y~)
\end{array}\qquad
% coordinates of midpoint
\left(\cfrac{ x_2 + x_1}{2}\quad ,\quad \cfrac{ y_2 + y_1}{2} \right)
\\\\\\
\left(\cfrac{x+0}{2}~~,~~\cfrac{y+2}{2} \right)=\stackrel{midpoint~T}{(0~,~5)}\implies
\begin{cases}
\cfrac{x+0}{2}=0\\\\
\boxed{x=0}\\
------\\
\cfrac{y+2}{2}=5\\\\
y+2=10\\
\boxed{y=8}
\end{cases}[/tex]
