6:9= 10

$$ 6 : \frac{9}{10} = \frac{6}{1} : \frac{9}{10} = \frac{6}{1} \cdot \frac{10}{9} = \frac{6 \cdot 10}{1 \cdot 9} = \frac{2 \cdot 10}{1 \cdot 3} = \frac{20}{3} = 6 \frac{2}{3} $$

Ответ: $$6 \frac{2}{3}$$