а) $$2 + \frac{4}{7} = 2\frac{4}{7} = \frac{2 \cdot 7 + 4}{7} = \frac{14 + 4}{7} = \frac{18}{7}$$.
б) $$10 + \frac{20}{30} = 10\frac{20}{30} = \frac{10 \cdot 30 + 20}{30} = \frac{300 + 20}{30} = \frac{320}{30}$$.
в) $$34 + \frac{46}{67} = 34\frac{46}{67} = \frac{34 \cdot 67 + 46}{67} = \frac{2278 + 46}{67} = \frac{2324}{67}$$.
Ответ: а) $$2\frac{4}{7} = \frac{18}{7}$$; б) $$10\frac{20}{30} = \frac{320}{30}$$; в) $$34\frac{46}{67} = \frac{2324}{67}$$.