4) 53: 5

4) $$5\frac{3}{5}: \frac{3}{7} = \frac{5 \cdot 5 + 3}{5} : \frac{3}{7} = \frac{28}{5} : \frac{3}{7} = \frac{28}{5} \cdot \frac{7}{3} = \frac{28 \cdot 7}{5 \cdot 3} = \frac{196}{15} = 13 \frac{1}{15}$$

Ответ: $$13 \frac{1}{15}$$