40 20 3 50 5 4

\[ \frac{40}{50} \div \frac{20}{5} \div \frac{3}{4} = \frac{40}{50} \cdot \frac{5}{20} \cdot \frac{4}{3} = \frac{40 \cdot 5 \cdot 4}{50 \cdot 20 \cdot 3} = \frac{800}{3000} = \frac{4}{15} \]

Ответ: \(\frac{4}{15}\)