[tex]\bf ~~~~~~~~~~~~\textit{middle point of 2 points } \\\\ (\stackrel{x_1}{-8}~,~\stackrel{y_1}{5})\qquad (\stackrel{x_2}{-17}~,~\stackrel{y_2}{4}) \qquad \left(\cfrac{ x_2 + x_1}{2}~~~ ,~~~ \cfrac{ y_2 + y_1}{2} \right) \\\\\\ \left( \cfrac{-17-8}{2}~~,~~\cfrac{4+5}{2} \right)\implies \left( \cfrac{-25}{2}~~,~~\cfrac{9}{2} \right)\implies \left(-12\frac{1}{2}~,~4\frac{1}{2} \right)[/tex]
