$(\frac{4a^2}{b^3}{)}^2\ast <!--\; \ast \; -->x=\frac{6a}{b^2}$
$x=\frac{6a}{b^2}:(\frac{4a^2}{b^3}{)}^2=\frac{6a}{b^2}:\frac{16a^4}{b^6}=\frac{6a}{b^2}\ast <!--\; \ast \; -->\frac{b^6}{16a^4}=\frac{3}{1}\ast <!--\; \ast \; -->\frac{b^4}{8a^3}=\frac{3b^4}{8a^3}$
Ответ: $(\frac{4a^2}{b^3}{)}^2\ast <!--\; \ast \; -->\frac{3b^4}{8a^3}=\frac{6a}{b^2}$

$(\frac{2b^4}{3c}{)}^3:x=\frac{b^6}{12}$
$x=(\frac{2b^4}{3c}{)}^3:\frac{b^6}{12}=\frac{8b^{12}}{27c^3}:\frac{b^6}{12}=\frac{8b^{12}}{27c^3}\ast <!--\; \ast \; -->\frac{12}{b^6}=\frac{8b^6}{9c^3}\ast <!--\; \ast \; -->\frac{4}{1}=\frac{32b^6}{9c^3}$
Ответ: $(\frac{2b^4}{3c}{)}^3:\frac{32b^6}{9c^3}=\frac{b^6}{12}$