\(4\cdot5\cdot\frac{6}{12}\cdot10\cdot8=\left(4\cdot5\right)\cdot\left(\frac{6}{12}\cdot8\right)\cdot10\)
\(=20\cdot4\cdot10=800\)
\(\frac{4\times5\times6}{12\times10\times8}=\frac{4\times5\times6}{2\times6\times5\times2\times2\times4}=\frac{1}{2\times2\times2}=\frac{1}{8}\)