Chapter 1 - Tools of Geometry - 1-7 Midpoint and Distance in the Coordinate Plane - Practice and Problem-Solving Exercises - Page 54: 19

$S(12,-24)$

Use the midpoint formula to find the x-coordinate. $M=\frac{x_1+x_2}{2}$ $5=\frac{x_1+(-2)}{2}$ $5\times2=\frac{x_1-2}{2}\times2$ $10=x_1-2$ $10+2=x_1-2+2$ $12=x_1$ Use the midpoint formula to find the y-coordinate. $M=\frac{y_1+y_2}{2}$ $-8=\frac{y_1+8}{2}$ $-8\times2=\frac{y_1+8}{2}\times2$ $-16=y_1+8$ $-16-8=y_1+8-8$ $-24=y_1$