A midpoint has coordinates of [tex](-2, -1)[/tex] we will call them [tex](x_m, y_m)[/tex].
The coordinates of a midpoint are constructed from coordinates of enpoints [tex](x_1,y_1),(x_2,y_2)[/tex], namely as a divided sum.
[tex]
x_m=\frac{x_1+x_2}{2}\implies x_1=2x_m-x_2 \\
y_m=\frac{y_1+y_2}{2}\implies y_1=2y_m-y_2
[/tex]
Now insert the numbers.
[tex]
x_1=2(-2)-(-6)=2 \\
y_1=2(-1)-4=-6
[/tex]
The result is an endpoint at [tex](2,-6)[/tex].
