HELP ASAP

$\text{Given two points }p_1,~p_2, \text{ the midpoint of the segment joining them is given by}\\ m=\dfrac{p_1+p_2}{2} \\ \text{in this case }\\ m =\left( \dfrac{-4+28}{2},~\dfrac{9-29}{2}\right)=?$

I leave that bit of arithmetic to you.

Continuing on, we have $\frac{24}{2}, \frac{-20}{2}$. Thus, our answer is $(12,-10)$.