Answer
$\lt 1,0,-1\gt$
Work Step by Step
Given: Line of intersection of the planes $x+y+z=1$ and $x+z=0$
$n_1=\lt 1,1,1\gt$
and
$n_2=\lt 1,0,1\gt$
Take the cross product of the two normal vectors.
$n_1 \times n_2=\lt 1,1,1\gt \times \lt 1,0,1\gt$
$=\lt 1,0,-1\gt$
