1 Вычислите: a) \(\frac{3}{4} + \frac{4}{5}\); б) \(\frac{2}{3} + \frac{1}{7}\); в) \(\frac{2}{13} + 0\); г) \(\frac{5}{9} + \(\frac{2}{11}\); д) \(\frac{5}{12} + \frac{3}{4}\); e) \(\frac{5}{6} + \frac{7}{8}\).

a) \(\frac{3}{4} + \frac{4}{5} = \frac{3 \cdot 5 + 4 \cdot 4}{4 \cdot 5} = \frac{15 + 16}{20} = \frac{31}{20} = 1\frac{11}{20}\)

б) \(\frac{2}{3} + \frac{1}{7} = \frac{2 \cdot 7 + 1 \cdot 3}{3 \cdot 7} = \frac{14 + 3}{21} = \frac{17}{21}\)

в) \(\frac{2}{13} + 0 = \frac{2}{13}\)

г) \(\frac{5}{9} + \frac{2}{11} = \frac{5 \cdot 11 + 2 \cdot 9}{9 \cdot 11} = \frac{55 + 18}{99} = \frac{73}{99}\)

д) \(\frac{5}{12} + \frac{3}{4} = \frac{5 + 3 \cdot 3}{12} = \frac{5 + 9}{12} = \frac{14}{12} = \frac{7}{6} = 1\frac{1}{6}\)

e) \(\frac{5}{6} + \frac{7}{8} = \frac{5 \cdot 4 + 7 \cdot 3}{24} = \frac{20 + 21}{24} = \frac{41}{24} = 1\frac{17}{24}\)

Ответ: a) \(1\frac{11}{20}\); б) \(\frac{17}{21}\); в) \(\frac{2}{13}\); г) \(\frac{73}{99}\); д) \(1\frac{1}{6}\); e) \(1\frac{17}{24}\)