I need help with this problem.

[tex]\bf ~~~~~~~~~~~~\textit{middle point of 2 points } \\\\ P_1(\stackrel{x_1}{m}~,~\stackrel{y_1}{b})\qquad P_2(\stackrel{x_2}{0}~,~\stackrel{y_2}{0}) \qquad \left(\cfrac{ x_2 + x_1}{2}~~~ ,~~~ \cfrac{ y_2 + y_1}{2} \right) \\\\\\ \left( \cfrac{0+m}{2}~~,~~\cfrac{0+b}{2} \right)\implies \left( \frac{m}{2}~,~\frac{b}{2} \right)[/tex]