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

5. Найдите значение выражения:

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