\[\boxed{\text{273\ (273).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[1)\ 3a^{6}b^{8} = 3a^{2}b^{6} \cdot a^{4}b^{2}\]
\[2) - 12a^{2}b^{10} = 3a^{2}b^{6} \cdot ( - 4b^{4})\]
\[3) - 2,7a^{5}b^{7} =\]
\[= 3a^{2}b^{6} \cdot ( - 0,9a^{3}b)\]
\[4)\ 2\frac{2}{7}a^{20}b^{30} = \frac{16}{7}a^{20}b^{30} =\]
\[= 3a^{2}b^{6} \cdot \frac{16}{21}a^{18}b^{24}\]