Решение:
a) \(\frac{2}{2} + \frac{6}{6} - \frac{3}{18} = 1 + 1 - \frac{1}{6} = 2 - \frac{1}{6} = \frac{12}{6} - \frac{1}{6} = \frac{11}{6} = 1 \frac{5}{6}\)
б) \(8 \frac{25}{27} - (3 \frac{8}{9} + 2 \frac{1}{3}) = 8 \frac{25}{27} - (3 \frac{8}{9} + 2 \frac{3}{9}) = 8 \frac{25}{27} - 5 \frac{11}{9} = 8 \frac{25}{27} - 5 \frac{33}{27} = 7 \frac{52}{27} - 5 \frac{33}{27} = 2 \frac{19}{27}\)
в) \((8 \frac{3}{15} - 7 \frac{2}{45}) + 3 \frac{8}{5} = (8 \frac{9}{45} - 7 \frac{2}{45}) + 3 \frac{8}{5} = 1 \frac{7}{45} + 3 \frac{8}{5} = 1 \frac{7}{45} + 3 \frac{72}{45} = 4 \frac{79}{45} = 5 \frac{34}{45}\)
Ответ: a) \(1 \frac{5}{6}\); б) \(2 \frac{19}{27}\); в) \(5 \frac{34}{45}\)