4

Решение:

1. \( \frac{2}{3} \cdot \frac{3}{4} = \frac{6}{12} = \frac{1}{2} \)
2. \( \frac{1}{2} + \frac{1}{6} = \frac{3}{6} + \frac{1}{6} = \frac{4}{6} = \frac{2}{3} \)
3. \( \frac{2}{3} \cdot \frac{1}{4} = \frac{2}{12} = \frac{1}{6} \)

Ответ: \( \frac{1}{6} \)