78. Выполните деление: 1) 4/9 : 7/8; 2) 6/25 : 12/35; 3) 8/65 : 4/13; 4) 48/49 : 32/63.

Решение:

1. \( \frac{4}{9} : \frac{7}{8} = \frac{4}{9} \times \frac{8}{7} = \frac{32}{63} \)
2. \( \frac{6}{25} : \frac{12}{35} = \frac{6}{25} \times \frac{35}{12} = \frac{1}{5} \times \frac{7}{2} = \frac{7}{10} \)
3. \( \frac{8}{65} : \frac{4}{13} = \frac{8}{65} \times \frac{13}{4} = \frac{2}{5} \times 1 = \frac{2}{5} \)
4. \( \frac{48}{49} : \frac{32}{63} = \frac{48}{49} \times \frac{63}{32} = \frac{3}{1} \times \frac{9}{2} = \frac{27}{2} \)

Ответ: 1) \( \frac{32}{63} \); 2) \( \frac{7}{10} \); 3) \( \frac{2}{5} \); 4) \( \frac{27}{2} \).