Answer
$(-5,3)$
Work Step by Step
Step 1. Assume the coordinates of the other endpoint are $(x,y)$
Step 2. Use the formula for midpoint, we have $\frac{x+(-9)}{2}=-7$ and $\frac{y+9}{2}=6$
Step 3. Solve above equations to get $x=-5, y=3$, thus the other endpoint is $(-5,3)$
