Вычислите: 1) 2/3 + 5/8; 2) 7/12 - 3/8; 3) 11/16 - 5/8; 4) 6/35 + 3/10; 5) 8/15 - 4/9; 6) 4/15 + 7/12.

Решение:

1. \( \frac{2}{3} + \frac{5}{8} = \frac{2 \cdot 8 + 5 \cdot 3}{24} = \frac{16 + 15}{24} = \frac{31}{24} \)
2. \( \frac{7}{12} - \frac{3}{8} = \frac{7 \cdot 2 - 3 \cdot 3}{24} = \frac{14 - 9}{24} = \frac{5}{24} \)
3. \( \frac{11}{16} - \frac{5}{8} = \frac{11}{16} - \frac{5 \cdot 2}{16} = \frac{11 - 10}{16} = \frac{1}{16} \)
4. \( \frac{6}{35} + \frac{3}{10} = \frac{6 \cdot 2 + 3 \cdot 7}{70} = \frac{12 + 21}{70} = \frac{33}{70} \)
5. \( \frac{8}{15} - \frac{4}{9} = \frac{8 \cdot 3 - 4 \cdot 5}{45} = \frac{24 - 20}{45} = \frac{4}{45} \)
6. \( \frac{4}{15} + \frac{7}{12} = \frac{4 \cdot 4 + 7 \cdot 5}{60} = \frac{16 + 35}{60} = \frac{51}{60} = \frac{17}{20} \)

Ответ: 1) \( \frac{31}{24} \), 2) \( \frac{5}{24} \), 3) \( \frac{1}{16} \), 4) \( \frac{33}{70} \), 5) \( \frac{4}{45} \), 6) \( \frac{17}{20} \).