Let's find the simplest form of the following expression:

$$
\frac{\sqrt[11]{\left[\left(\sqrt[3]{a^{4} b^{2} c}\right)^{5} \cdot\left(\sqrt{a^{3} b^{2} c}\right)^{4}\right]^{3}}}{\sqrt[11]{a^{5}}}
$$
Performing the indicated operations, we get:

$$
\sqrt[11]{\frac{a^{20} b^{10} c^{5} \cdot a^{13} b^{12} c^{6}}{a^{5}}}=\sqrt[11]{a^{33} b^{22} c^{11}}=a^{3} b^{2} c
$$

(Raab Rezső, Győr.)

Number of solutions: 21.