\[14b^{2} \cdot \frac{2}{21}b^{4} = \frac{28}{21}b^{6} = \frac{4}{3}b^{6} \Longrightarrow\]
\[\Longrightarrow коэффициент\ \ \frac{4}{3};\ \ \]
\[степень\ 6.\]