Chapter 1 - Tools of Geometry - 1-7 Midpoint and Distance in the Coordinate Plane - Practice and Problem-Solving Exercises - Page 54: 18

$S(0,-34)$

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. $M=\frac{y_1+y_2}{2}$ $-8=\frac{y_1+18}{2}$ $-8\times2=\frac{y_1+18}{2}\times2$ $-16=y_1+18$ $-16-18=y_1+18-18$ $-34=y_1$