Упростите выражение a^3/3c:(ab^2/c:3b^3/a).

\[\frac{a^{3}}{3c}\ :\left( \frac{ab^{2}}{c}\ :\frac{3b^{3}}{a} \right) = \frac{a^{3}}{3c}\ :\left( \frac{ab^{2}}{c} \cdot \frac{a}{3b^{3}} \right) =\]

\[= \frac{a^{3}}{3c} \cdot \frac{3bc}{a^{2}} = ab\]