2. Вычислите: а) \( 7\frac{3}{9} + 4\frac{6}{9} \) б) \( 15\frac{3}{11} + 17\frac{8}{11} \) в) \( 9\frac{3}{4} \) г) \( 18\frac{3}{7} - 5\frac{6}{7} \)

Решение:

1. \( 7\frac{3}{9} + 4\frac{6}{9} = (7+4) + (\frac{3}{9} + \frac{6}{9}) = 11 + \frac{9}{9} = 11 + 1 = 12 \)
2. \( 15\frac{3}{11} + 17\frac{8}{11} = (15+17) + (\frac{3}{11} + \frac{8}{11}) = 32 + \frac{11}{11} = 32 + 1 = 33 \)
3. \( 9\frac{3}{4} = \frac{9 \times 4 + 3}{4} = \frac{36 + 3}{4} = \frac{39}{4} \)
4. \( 18\frac{3}{7} - 5\frac{6}{7} = (17 + \frac{7+3}{7}) - 5\frac{6}{7} = 17\frac{10}{7} - 5\frac{6}{7} = (17-5) + (\frac{10}{7} - \frac{6}{7}) = 12 + \frac{4}{7} = 12\frac{4}{7} \)

Ответ: а) 12; б) 33; в) \(\frac{39}{4}\); г) \(12\frac{4}{7}\).