The simultaneous equations on the Boolean variables $x, y, z$ and $w$,
- $x + y + z = 1 $
- $xy = 0$
- $xz + w = 1$
- $xy + \bar{z}\bar{w} = 0$
have the following solution for $x, y, z$ and $w,$ respectively:
- $0 \ 1 \ 0 \ 0$
- $1 \ 1 \ 0 \ 1$
- $1 \ 0 \ 1 \ 1$
- $1 \ 0 \ 0 \ 0$