571. г) \( \left(\frac{9}{13} - \frac{9}{39}\right) \cdot 9 \);

\( \frac{9}{13} - \frac{9}{39} = \frac{27}{39} - \frac{9}{39} = \frac{18}{39} = \frac{6}{13} \). Теперь умножаем: \( \frac{6}{13} \cdot 9 = \frac{54}{13} \approx 4.154 \).