4 1 5 2

\[ \frac{4}{5} \div \frac{1}{2} = \frac{4}{5} \cdot \frac{2}{1} = \frac{4 \cdot 2}{5 \cdot 1} = \frac{8}{5} = 1\frac{3}{5} \]

Ответ: \(1\frac{3}{5}\)