(1) a/(x-a)+b=1 (b≠1)
a/(x-a)=1-b
x-a=a/(1-b)
x=a+a/(1-b)
x=a(2-b)/(1-b)
2) m/x-n/(x+1)=0 (m≠n,mn≠0)
m/x=n/(x+1)
m(x+1)=nx
mx-nx=-m
(m-n)x=-m
x=-m/(m-n)