The general formula for midpoint is
[tex]x_m,y_m=\frac{x_1+x_2}{2},\text{ }\frac{y_1+y_2}{2}[/tex]Here coordinates of midpoint M is
[tex]x_m,y_m=(-4,5)[/tex]Coordinates of S is
[tex]x_2,y_2=\text{ }(0,-10)[/tex]Substitute in midpoint formula
[tex]\begin{gathered} -4=\frac{x_1+0}{2} \\ -4\ast2=x_1 \\ x_1=-8 \\ \\ \\ coordinatey_1 \\ \\ 5=\frac{y_1+(-10)}{2} \\ 5\ast2=y_1-10 \\ 10=y_1-10 \\ y_1=10+10=20 \end{gathered}[/tex]The coordinates of R is x1, y1=(-8,20)
