mx-y=m
y=mx-m=m(x-1) ...(1)
x+my=m-1
x+m*m(x-1)=m-1
x+m^2x-m^2=m-1
(m^2+1)x=m^2+m-1
x=(m^2+m-1)/(m^2+1)
y=m[(m^2+m-1)/(m^2+1)-1]
=m[m^2+m-1-m^2-1]/(m^2+1)
=m^2/(m^2+1)