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