\[\boxed{\text{997\ (997).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[b_{1} + b_{2} = 30,\ \ b_{2} + b_{3} = 20,\]
\[b_{2} = b_{1} \cdot q = 18 \cdot \frac{2}{3} = 12,\]
\[b_{3} = b_{2} \cdot q = 12 \cdot \frac{2}{3} = 8.\]
\[Ответ:18,\ 12,\ 8.\]