Б) (2/5 + 5/8 - 11/12) · 1/3

Решение:

\( (\frac{2}{5} + \frac{5}{8} - \frac{11}{12}) \cdot \frac{1}{3} \)

1. \( \frac{2}{5} + \frac{5}{8} - \frac{11}{12} = \frac{2 \cdot 24}{120} + \frac{5 \cdot 15}{120} - \frac{11 \cdot 10}{120} = \frac{48 + 75 - 110}{120} = \frac{13}{120} \)
2. \( \frac{13}{120} \cdot \frac{1}{3} = \frac{13}{360} \)

Ответ: \( \frac{13}{360} \)