Answer
$S(0,-34)$
Work Step by Step
Use the midpoint formula to find the x-coordinate.
$M=\frac{x_1+x_2}{2}$
$5=\frac{x_1+10}{2}$
$5\times2=\frac{x_1+10}{2}\times2$
$10=x_1+10$
$10-10=x_1+10-10$
$0=x_1$
Use the midpoint formula to find the y-coordinate.
$M=\frac{y_1+y_2}{2}$
$-8=\frac{y_1+18}{2}$
$-8\times2=\frac{y_1+18}{2}\times2$
$-16=y_1+18$
$-16-18=y_1+18-18$
$-34=y_1$