Решение:
$$1 \frac{13}{14} - (2 - 1 \frac{11}{35}) : \frac{9}{25} + \frac{4}{21} = \frac{27}{14} - (\frac{70}{35} - \frac{46}{35}) : \frac{9}{25} + \frac{4}{21} = \frac{27}{14} - \frac{24}{35} : \frac{9}{25} + \frac{4}{21} = \frac{27}{14} - \frac{24}{35} \cdot \frac{25}{9} + \frac{4}{21} = \frac{27}{14} - \frac{8 \cdot 5}{7 \cdot 3} + \frac{4}{21} = \frac{27}{14} - \frac{40}{21} + \frac{4}{21} = \frac{81}{42} - \frac{80}{42} + \frac{8}{42} = \frac{1}{42} + \frac{8}{42} = \frac{9}{42} = \frac{3}{14}$$
Ответ: $$\frac{3}{14}$$