Question

A/1-b+a-ab/b-1*b+1/a

Answer 1

$frac{a}{1-b} +frac{a-ab}{b-1} cdot frac{b+1}{a} = frac{a}{-(b-1)} + frac{-a(b-1)(b+1)}{a(b-1)} = -frac{a}{b-1} -(b+1)=\\= frac{-a-(b^2-1)}{b-1} = frac{1-a-b^2}{b-1}$