Ответ:

а) \(\frac{6x^3y^2}{15xy^3}=\frac{2x^2}{5y}\).

б) \(\frac{2b+18}{b^2+18b+81}=\frac{2(b+9)}{(b+9)^2}=\frac{2}{b+9}\).

в) \(\frac{y^2-2y+1}{1-y^2}=\frac{(y-1)^2}{(1-y)(1+y)}=\frac{1-y}{1+y}\).

Ответ: а) \(\frac{2x^2}{5y}\); б) \(\frac{2}{b+9}\); в) \(\frac{1-y}{1+y}\).