Решение:
1. $$\frac{9}{14} : 2 = \frac{9}{14} \cdot \frac{1}{2} = \frac{9}{28}$$
2. $$\frac{5}{2} \cdot \frac{4}{35} = \frac{5 \cdot 4}{2 \cdot 35} = \frac{20}{70} = \frac{2}{7}$$
3. $$\frac{9}{28} + \frac{2}{7} = \frac{9}{28} + \frac{2 \cdot 4}{7 \cdot 4} = \frac{9}{28} + \frac{8}{28} = \frac{9+8}{28} = \frac{17}{28}$$
Ответ: $$\frac{17}{28}$$