а) $$4 + \frac{2}{7} = \frac{4 \cdot 7}{7} + \frac{2}{7} = \frac{28}{7} + \frac{2}{7} = \frac{28+2}{7} = \frac{30}{7} = 4\frac{2}{7}$$
Ответ: $$4\frac{2}{7}$$
б) $$9 - \frac{6}{14} = \frac{9 \cdot 14}{14} - \frac{6}{14} = \frac{126}{14} - \frac{6}{14} = \frac{126-6}{14} = \frac{120}{14} = \frac{60}{7} = 8\frac{4}{7}$$
Ответ: $$8\frac{4}{7}$$
в) $$\frac{35}{54} - \frac{29}{54} = \frac{35-29}{54} = \frac{6}{54} = \frac{1}{9}$$
Ответ: $$\frac{1}{9}$$
г) $$\frac{18}{75} + \frac{46}{75} = \frac{18+46}{75} = \frac{64}{75}$$
Ответ: $$\frac{64}{75}$$