6) -2/3 * (-9/16)

6) $$\frac{-2}{3} \cdot (\frac{-9}{16}) = \frac{2}{3} \cdot \frac{9}{16} = \frac{2 \cdot 9}{3 \cdot 16} = \frac{18}{48} = \frac{3}{8}$$

Ответ: 0,375