$$7\frac{5}{7} : 1,2 = \frac{54}{7} : \frac{12}{10} = \frac{54}{7} : \frac{6}{5} = \frac{9}{7} \cdot \frac{5}{1} = \frac{45}{7} = 6\frac{3}{7}$$
Ответ: $$6\frac{3}{7}$$