subtract b from both sides$y-b=a\frac{t-1}{t+1}$divide both sides by a$\frac{y-b}{a}=\frac{t-1}{t+1}$multiply by t+1$(\frac{y-b}{a})(1+t)=t-1$use Distributive Property for left side$(\frac{y-b}{a})+(\frac{y-b}{a})t=t-1$isolate the terms including t$(\frac{y-b}{a})t-t=-1-(\frac{y-b}{a})$factor out t from left side$t((\frac{y-b}{a})-1)=-1-(\frac{y-b}{a})$finally u have$t=\frac{-1-(\frac{y-b}{a})}{(\frac{y-b}{a})-1}$