Answer
${(x, y, z) | x-5y-2z=6}$
Work Step by Step
$x-5y-2z=6$
$-2x+10y+4z=-12$
$1/2*x-5/2*y-z=3$
$1/2*x-5/2*y-z=3$
$2*(1/2*x-5/2*y-z)=3*2$
$x-5y-2z=6$
$-2x+10y+4z=-12$
$(-2x+10y+4z)/-2=-12/-2$
$x-5y-2z=6$
$x-5y-2z=6$
$x-5y-2z=6$
$x-5y-2z=6$
All three lines are the same, so their solution is ${(x, y, z) | x-5y-2z=6}$.
