68 Выполните сложение и вычитание: a) \(\frac{4}{9} + \frac{2}{9}\); б) \(1 \frac{1}{11} + \frac{5}{11}\); в) \(\frac{12}{19} + \frac{7}{19}\); г) \(\frac{13}{1000} + \frac{26}{1000}\); д) \(\frac{5}{7} - \frac{2}{7}\); e) \(\frac{4}{6} - \frac{2}{6}\); ж) \(\frac{11}{16} - \frac{4}{16}\); з) \(\frac{47}{100} - \frac{26}{100}\);

a) \(\frac{4}{9} + \frac{2}{9} = \frac{4+2}{9} = \frac{6}{9} = \frac{2}{3}\) б) \(1 \frac{1}{11} + \frac{5}{11} = \frac{12}{11} + \frac{5}{11} = \frac{12+5}{11} = \frac{17}{11} = 1 \frac{6}{11}\) в) \(\frac{12}{19} + \frac{7}{19} = \frac{12+7}{19} = \frac{19}{19} = 1\) г) \(\frac{13}{1000} + \frac{26}{1000} = \frac{13+26}{1000} = \frac{39}{1000}\) д) \(\frac{5}{7} - \frac{2}{7} = \frac{5-2}{7} = \frac{3}{7}\) e) \(\frac{4}{6} - \frac{2}{6} = \frac{4-2}{6} = \frac{2}{6} = \frac{1}{3}\) ж) \(\frac{11}{16} - \frac{4}{16} = \frac{11-4}{16} = \frac{7}{16}\) з) \(\frac{47}{100} - \frac{26}{100} = \frac{47-26}{100} = \frac{21}{100}\)