\(coordinates\ of\ E(x,y)\\\\
midpoint:\ C(-2,-1)\\
endpoint:\ A(-3,1) \\\\
B(-2,-1)=(\frac{-3+x}{2}\ ;\ \frac{1+y}{2})\\\\
-2=\frac{-3+x}{2}\ \ | multiply\ by\ 2\\
-4=-3+x\ \ | add\ 3\\
-1=x\\\\
-1=\frac{1+y}{2}\ \ | multiply\ by\ 2\\
-2=1+y\ \ \ | subtract\ 1\\
-3=y\\\\Coordinate\ of\ C=(-1,-3)\)
