ж) 2 1/7 : 1 11/14;

$$2 \frac{1}{7} : 1 \frac{11}{14} = \frac{15}{7} : \frac{25}{14} = \frac{15}{7} \cdot \frac{14}{25} = \frac{15 \cdot 14}{7 \cdot 25} = \frac{3 \cdot 5 \cdot 2 \cdot 7}{7 \cdot 5 \cdot 5} = \frac{3 \cdot 2}{5} = \frac{6}{5} = 1 \frac{1}{5}$$