\[\boxed{\text{460\ (460).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[1)\ 3a^{- 6}b^{2} \cdot 0,4a^{- 2}b^{- 5} =\]
\[= 1,2a^{- 8}b^{- 3} = \frac{6}{5a^{8}b^{3}}\]
\[2)\frac{4,8a^{2}b^{- 4}}{0,6a^{3}b^{- 6}} = \frac{8b^{2}}{a}\text{.\ }\]
\[\boxed{\text{460.}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[\left\{ 4;6;8 \right\}:\]
\[\left\{ 4 \right\};\left\{ 6 \right\};\left\{ 8 \right\};\left\{ \varnothing \right\};\]
\[\left\{ 4;6 \right\};\ \ \left\{ 4;8 \right\};\ \ \left\{ 6;8 \right\}.\]