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
