Задание 31. Найдите разность.

Решение:

1. \( \frac{8}{15} - \frac{2}{30} = \frac{8 \cdot 2}{15 \cdot 2} - \frac{2}{30} = \frac{16}{30} - \frac{2}{30} = \frac{16 - 2}{30} = \frac{14}{30} = \frac{7}{15} \)
2. \( \frac{25}{30} - \frac{4}{30} = \frac{21}{30} = \frac{7}{10} \)
3. \( \frac{21}{30} - \frac{7}{10} = \frac{21}{30} - \frac{7 \cdot 3}{10 \cdot 3} = \frac{21}{30} - \frac{21}{30} = 0 \)