6.58 Найдите сумму: a) \(\frac{8}{13} + \frac{3}{13}\); б) \(\frac{31}{60} + \frac{29}{60}\); в) \(18 + \frac{4}{19}\); г) \(23 + \frac{9}{10}\); д) \(2\frac{7}{9} + \frac{8}{9}\); е) \(15\frac{8}{11} + 4\frac{3}{11}\); ж) \(4\frac{1}{2} + 3\frac{1}{4}\); з) \(5\frac{7}{21} + 3\frac{20}{21}\).

Ответ: a) \(\frac{11}{13}\); б) 1; в) \(18\frac{4}{19}\); г) \(23\frac{9}{10}\); д) \(3\frac{6}{9}\); е) 20; ж) \(7\frac{3}{4}\); з) \(9\frac{6}{21}\)

a) \(\frac{8}{13} + \frac{3}{13} = \frac{8+3}{13} = \frac{11}{13}\)

б) \(\frac{31}{60} + \frac{29}{60} = \frac{31+29}{60} = \frac{60}{60} = 1\)

в) \(18 + \frac{4}{19} = 18\frac{4}{19}\)

г) \(23 + \frac{9}{10} = 23\frac{9}{10}\)

д) \(2\frac{7}{9} + \frac{8}{9} = 2 + \frac{7}{9} + \frac{8}{9} = 2 + \frac{15}{9} = 2 + 1\frac{6}{9} = 3\frac{6}{9}\)

е) \(15\frac{8}{11} + 4\frac{3}{11} = 15 + 4 + \frac{8}{11} + \frac{3}{11} = 19 + \frac{11}{11} = 19 + 1 = 20\)

ж) \(4\frac{1}{2} + 3\frac{1}{4} = 4\frac{2}{4} + 3\frac{1}{4} = 7\frac{3}{4}\)

з) \(5\frac{7}{21} + 3\frac{20}{21} = 5 + 3 + \frac{7}{21} + \frac{20}{21} = 8 + \frac{27}{21} = 8 + 1\frac{6}{21} = 9\frac{6}{21}\)

Ответ: a) \(\frac{11}{13}\); б) 1; в) \(18\frac{4}{19}\); г) \(23\frac{9}{10}\); д) \(3\frac{6}{9}\); е) 20; ж) \(7\frac{3}{4}\); з) \(9\frac{6}{21}\)