Answer
$(2,-1,1)$
Work Step by Step
To solve the given problem we will have to plug the simplest equation into the other equation and then solve for the other variable.
$9x+3z=21$ and $x-2z=0$
This gives $x=2$
Now, $2-2z=0$ or, $z=1$
Also, $2+2y-1=-1$ or, $2y+1=-1$
or, $2y=-2$
or, $y=-1$
Hence, the desired result is: $(2,-1,1)$
