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\(\frac{7}{9}\) + \(\frac{8}{9}\); e) 15\(\frac{8}{11}\) + 4\(\frac{3}{11}\); ж) 4\(\frac{1}{2}\) + 3\(\frac{1}{2}\); з) 5\(\frac{1}{7}\) + 3\(\frac{20}{21}\)

Ответ: a) \(\frac{11}{13}\); б) 1; в) 18\(\frac{4}{19}\); г) 23\(\frac{9}{10}\); д) 3\(\frac{5}{9}\); e) 20\(\frac{1}{11}\); ж) 8; з) 8\(\frac{4}{21}\)

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

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

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

ж) \(4\frac{1}{2} + 3\frac{1}{2} = 4 + 3 + \frac{1}{2} + \frac{1}{2} = 7 + \frac{1+1}{2} = 7 + \frac{2}{2} = 7 + 1 = 8\)

з) \(5\frac{1}{7} + 3\frac{20}{21} = 5\frac{3}{21} + 3\frac{20}{21} = 5 + 3 + \frac{3}{21} + \frac{20}{21} = 8 + \frac{3+20}{21} = 8 + \frac{23}{21} = 8 + 1\frac{2}{21} = 9\frac{2}{21}\)

Ответ: a) \(\frac{11}{13}\); б) 1; в) 18\(\frac{4}{19}\); г) 23\(\frac{9}{10}\); д) 3\(\frac{5}{9}\); e) 20\(\frac{1}{11}\); ж) 8; з) 8\(\frac{4}{21}\)