5. Найдите значение выражения: a) 7/15 + 3/10; б) 7/15 - 3/10; в) 5/12 * 9/20; г) 5/12 : 9/20; д) (5/7 + 3 14/18) + 2/7; е) 16 19/40 - (13 + 1 19/40).

a) \(\frac{7}{15} + \frac{3}{10} = \frac{14}{30} + \frac{9}{30} = \frac{23}{30}\) б) \(\frac{7}{15} - \frac{3}{10} = \frac{14}{30} - \frac{9}{30} = \frac{5}{30} = \frac{1}{6}\) в) \(\frac{5}{12} \cdot \frac{9}{20} = \frac{5 \cdot 9}{12 \cdot 20} = \frac{45}{240} = \frac{3}{16}\) г) \(\frac{5}{12} : \frac{9}{20} = \frac{5}{12} \cdot \frac{20}{9} = \frac{5 \cdot 20}{12 \cdot 9} = \frac{100}{108} = \frac{25}{27}\) д) \((\frac{5}{7} + 3\frac{14}{18}) + \frac{2}{7} = (\frac{5}{7} + \frac{2}{7}) + 3\frac{7}{9} = 1 + 3\frac{7}{9} = 4\frac{7}{9}\) е) \(16\frac{19}{40} - (13 + 1\frac{19}{40}) = 16\frac{19}{40} - 13 - 1\frac{19}{40} = (16 - 13 - 1) + (\frac{19}{40} - \frac{19}{40}) = 2 + 0 = 2\)