\(\dfrac{9 a}{a^2+a b} \cdot \dfrac{a b+b^2}{3 b^2}\).

\(\dfrac{b-a}{a} \cdot \dfrac{3 a}{a^2-b^2}\).

\(\dfrac{3+x}{x^3-y x^2} \cdot \dfrac{x^2-y^2}{x^2-9}: \dfrac{x+y}{x^2}\).

\((a+b) \cdot\left(\dfrac{1}{a}-\dfrac{1}{b}\right) \cdot\left(\dfrac{a^2-b^2}{a b}\right)^{-1}\)

\(\left(\dfrac{a-2}{a+2}-\dfrac{a+2}{a-2}\right) \cdot\left(\dfrac{4 a}{a^2-4}\right)^{-1}\)

\(\left(\dfrac{a-2}{a^2-4}+\dfrac{a^2-4}{a+2}+2-a\right) \cdot(a+2)\).

\(\left(\dfrac{(a-b)^2}{2 a}+b\right): \dfrac{a^2+b^2}{2 a^2}\).

\(\left(\dfrac{a}{a b-b^2}-\dfrac{b}{a^2-a b}\right): \dfrac{a^2-b^2}{a b}\).

\(\dfrac{b^3+b^2-b-1}{b^2+b+b+1}+\dfrac{2 b+2}{b+1}\)

\(\dfrac{3 x^3-x^2-27 x+9}{2 x^3+3 x^2-18 x-27}+\dfrac{x+7}{2 x+3}\).