5.278 Найдите сумму: a) $$7 + 2\frac{5}{8}$$; б) $$9\frac{1}{9} + 20$$; в) $$64\frac{5}{7} + 4\frac{4}{7}$$; г) $$7\frac{5}{19} + 4\frac{1}{19}$$.

a) $$7 + 2\frac{5}{8}$$

$$7 + 2\frac{5}{8} = 7 + 2 + \frac{5}{8} = 9 + \frac{5}{8} = 9\frac{5}{8}$$

Ответ: $$9\frac{5}{8}$$

б) $$9\frac{1}{9} + 20$$

$$9\frac{1}{9} + 20 = 9 + \frac{1}{9} + 20 = 29 + \frac{1}{9} = 29\frac{1}{9}$$

Ответ: $$29\frac{1}{9}$$

в) $$64\frac{5}{7} + 4\frac{4}{7}$$

$$64\frac{5}{7} + 4\frac{4}{7} = (64 + 4) + (\frac{5}{7} + \frac{4}{7}) = 68 + \frac{9}{7} = 68 + 1\frac{2}{7} = 69\frac{2}{7}$$

Ответ: $$69\frac{2}{7}$$

г) $$7\frac{5}{19} + 4\frac{1}{19}$$

$$7\frac{5}{19} + 4\frac{1}{19} = (7 + 4) + (\frac{5}{19} + \frac{1}{19}) = 11 + \frac{6}{19} = 11\frac{6}{19}$$

Ответ: $$11\frac{6}{19}$$