\[b_{1} = - 27;\ \ \ q = \frac{1}{3}\]
\[b_{6} = b_{1}q^{5} = - 27 \cdot \left( \frac{1}{3} \right)^{5} =\]
\[= - 27 \cdot \frac{1}{243} = - \frac{1}{9}.\]