\[{\text{Вычислите: }}\frac{{{{21}^{12}}}}{{{{\left( {{7^4}} \right)}^3} \cdot {{\left( {{3^2}} \right)}^4}}}.\]

\[{\text{Вычислите: }}\frac{{{5^{2k + 4}} \cdot {4^{2k + 6}}}}{{80 \cdot {{20}^{2k + 3}}}}.\]