2. Найти значение выражения: a) \(5\frac{11}{30} + 24\frac{19}{30}\); б) \(9 - 3\frac{5}{12}\); в) \(\frac{5}{11} + 2\frac{3}{11} + 5\frac{7}{11}\); г) \(9\frac{13}{19} + (8\frac{18}{19} - 3\frac{15}{19})\); д) \(10\frac{4}{21} - (4\frac{6}{21} + 3\frac{11}{21})\)

1. \(5\frac{11}{30} + 24\frac{19}{30} = (5 + 24) + (\frac{11}{30} + \frac{19}{30}) = 29 + \frac{30}{30} = 29 + 1 = 30\)
2. \(9 - 3\frac{5}{12} = 8\frac{12}{12} - 3\frac{5}{12} = (8 - 3) + (\frac{12}{12} - \frac{5}{12}) = 5 + \frac{7}{12} = 5\frac{7}{12}\)
3. \(\frac{5}{11} + 2\frac{3}{11} + 5\frac{7}{11} = (2 + 5) + (\frac{5}{11} + \frac{3}{11} + \frac{7}{11}) = 7 + \frac{15}{11} = 7 + 1\frac{4}{11} = 8\frac{4}{11}\)
4. \(9\frac{13}{19} + (8\frac{18}{19} - 3\frac{15}{19}) = 9\frac{13}{19} + ((8-3) + (\frac{18}{19} - \frac{15}{19})) = 9\frac{13}{19} + (5 + \frac{3}{19}) = (9 + 5) + (\frac{13}{19} + \frac{3}{19}) = 14 + \frac{16}{19} = 14\frac{16}{19}\)
5. \(10\frac{4}{21} - (4\frac{6}{21} + 3\frac{11}{21}) = 10\frac{4}{21} - ((4 + 3) + (\frac{6}{21} + \frac{11}{21})) = 10\frac{4}{21} - (7 + \frac{17}{21}) = 10\frac{4}{21} - 7\frac{17}{21} = 9\frac{25}{21} - 7\frac{17}{21} = (9 - 7) + (\frac{25}{21} - \frac{17}{21}) = 2 + \frac{8}{21} = 2\frac{8}{21}\)

Ответ: a) 30; б) \(5\frac{7}{12}\); в) \(8\frac{4}{11}\); г) \(14\frac{16}{19}\); д) \(2\frac{8}{21}\)