И) (1/6 + 1/10 + 1/15) : (3/5 − 1/3 − 1/4)

Решение:

\( (\frac{1}{6} + \frac{1}{10} + \frac{1}{15}) : (\frac{3}{5} - \frac{1}{3} - \frac{1}{4}) \)

1. \( \frac{1}{6} + \frac{1}{10} + \frac{1}{15} = \frac{5}{30} + \frac{3}{30} + \frac{2}{30} = \frac{10}{30} = \frac{1}{3} \)
2. \( \frac{3}{5} - \frac{1}{3} - \frac{1}{4} = \frac{36}{60} - \frac{20}{60} - \frac{15}{60} = \frac{1}{60} \)
3. \( \frac{1}{3} : \frac{1}{60} = \frac{1}{3} \cdot 60 = 20 \)

Ответ: 20