Answer
($2x_{m}$ - $x_{1}$ , $2y_{m}$ - $y_{1}$)
Work Step by Step
Use the midpoint formula and equate the x--coordinates and y-coordinates respectively and solve for $x_{2}$ and $y_{2}$.
($x_{m},y_{m}$) = $(\frac{x_{1}+x_{2}}{2},\frac{y_{1}+y_{2}}{2})$
$x_{2}$ = $2x_{m}$ - $x_{1}$
$y_{2}$= $2y_{m}$ - $y_{1}$
