x=(1-t)/(1+t)
x+tx=1-t
t(x+1)=1-x
t=1-x)/(1+x)
y=(2-3t)/(3-2t)
=[2-3*(1-x)/(1+x)]/[(3-2*(1-x)/(1+x)]
=[(5x-1)/(1+x)]/[(5x+1)/(1+x)]
=(5x-1)/(5x+1)