Представим смешанное число в виде неправильной дроби:
$$1 \frac{1}{13} = \frac{1 \cdot 13 + 1}{13} = \frac{14}{13}$$
- $$c = 1$$ $$\frac{14}{13} : 1 = \frac{14}{13} = 1\frac{1}{13}$$
$$\frac{14}{13} = 1\frac{1}{13}$$
- $$c = \frac{2}{13}$$ $$\frac{14}{13} : \frac{2}{13} = \frac{14}{13} \cdot \frac{13}{2} = 7$$
$$7 > 1\frac{1}{13}$$
- $$c = \frac{1}{7}$$ $$\frac{14}{13} : \frac{1}{7} = \frac{14}{13} \cdot 7 = \frac{98}{13} = 7\frac{7}{13}$$
$$7\frac{7}{13} > 1\frac{1}{13}$$
- $$c = \frac{14}{9}$$ $$\frac{14}{13} : \frac{14}{9} = \frac{14}{13} \cdot \frac{9}{14} = \frac{9}{13}$$
$$\frac{9}{13} < 1\frac{1}{13}$$
Ответ: $$ \frac{9}{13} < 1\frac{1}{13} < 7 < 7\frac{7}{13}$$