Answer
$x=2$
$y=1$
$z=-3$
Work Step by Step
Express z from the second equation.
$x-y-z=4$
$2y+z=-1\rightarrow z=-1-2y$
$-x+y-2z=5$
Substitute $ z=-1-2y$ into the first and the third equation.
$x-y-(-1-2y)=4$
$-x+y-2(-1-2y)=5$
Simplify.
$x+y=3$
$-x+5y=3$
Add the equations to eliminate x.
$6y=6$
$y=1$
Substitute for y and solve for x and z.
$z=-3$
$x=2$
