4) \frac{45a^{4}b^{2}}{49c^{3}d} : \frac{9a^{3}b^{2}}{14cd};

4) \(\frac{45a^{4}b^{2}}{49c^{3}d} : \frac{9a^{3}b^{2}}{14cd} = \frac{45a^{4}b^{2}}{49c^{3}d} \cdot \frac{14cd}{9a^{3}b^{2}} = \frac{45 \cdot 14 \cdot a^{4}b^{2}cd}{49 \cdot 9 \cdot a^{3}b^{2}c^{3}d} = \frac{10a}{7c^{2}}\)

Ответ: \(\frac{10a}{7c^{2}}\)