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

a) \[7 + 2\frac{5}{8} = 7 + \frac{2 \cdot 8 + 5}{8} = 7 + \frac{16 + 5}{8} = 7 + \frac{21}{8} = 7 + 2\frac{5}{8} = 9\frac{5}{8}\] б) \[9\frac{1}{9} + 20 = \frac{9 \cdot 9 + 1}{9} + 20 = \frac{81 + 1}{9} + 20 = \frac{82}{9} + 20 = 9\frac{1}{9} + 20 = 29\frac{1}{9}\] в) \[64\frac{1}{7} + 4\frac{4}{7} = (64 + 4) + (\frac{1}{7} + \frac{4}{7}) = 68 + \frac{1+4}{7} = 68 + \frac{5}{7} = 68\frac{5}{7}\] г) \[7\frac{5}{7} + 4 = 11\frac{5}{7}\]

Ответ: a) \[9\frac{5}{8}\]; б) \[29\frac{1}{9}\]; в) \[68\frac{5}{7}\]; г) \[11\frac{5}{7}\]