a) $$2 + \frac{4}{7} = 2 \frac{4}{7} = \frac{2 \cdot 7 + 4}{7} = \frac{14 + 4}{7} = \frac{18}{7}$$.
б) $$10 + \frac{20}{30} = 10 + \frac{2}{3} = 10 \frac{2}{3} = \frac{10 \cdot 3 + 2}{3} = \frac{30 + 2}{3} = \frac{32}{3}$$.
в) $$34 + \frac{46}{67} = 34 \frac{46}{67} = \frac{34 \cdot 67 + 46}{67} = \frac{2278 + 46}{67} = \frac{2324}{67}$$.
Ответ: a) $$2 \frac{4}{7} = \frac{18}{7}$$; б) $$10 \frac{2}{3} = \frac{32}{3}$$; в) $$34 \frac{46}{67} = \frac{2324}{67}$$