\[q = \frac{1}{3}\]
\[\frac{b_{6} \cdot b_{8}}{b_{7} \cdot b_{9}} = \frac{b_{1}q^{5} \cdot b_{1}q^{7}}{b_{1}q^{6} \cdot b_{1}q^{8}} = \frac{q^{12}}{q^{14}} =\]
\[= \frac{1}{q^{2}} = \frac{1}{\left( \frac{1}{3} \right)^{2}} = \frac{1}{\frac{1}{9}} = 9\]
\[Ответ:\ \ 9.\]