Ответ:\(\frac{4}{13}:5=\frac{4}{13}\cdot\frac{1}{5}=\frac{4}{65}\).\(\frac{a}{b}:c=\frac{a}{bc}\).\(12:\frac{8}{9}=12\cdot\frac{9}{8}=\frac{27}{2}\).\(a:\frac{b}{c}=\frac{ac}{b}\).