Question

X+y+z=1 X-2y+3z=2 X+z-5=0

Answer 1

x+y+z=1

x=1/(y+z)

1/(y+z)-2y+3z=2  

1-2y²-2yz+3yz+3z²=2(y+z)

(1-2y²+yz+3z²)/2=y+z

z=(1-2y²+yz+3z²)/2 -y/1

z=(1-2y²+yz+3z²-2y)/2