58 Найдите сумму: a) \frac{8}{13} + \frac{3}{13}; 6) \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}{4}; з) 5\frac{1}{7} + 3\frac{20}{21}.

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

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

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

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

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

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

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

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

Ответ: a) \(\frac{11}{13}\); б) 1; в) \(18\frac{4}{19}\); г) \(23\frac{9}{10}\); д) \(3\frac{2}{3}\); e) 20; ж) \(7\frac{3}{4}\); з) \(9\frac{2}{21}\)