\[\boxed{\mathbf{6}.}\]
\[1)\ \left( 8x^{3} - 4x^{2} + 6x \right)\ :( - 2x) =\]
\[= - 4x^{2} + 2x - 3\]
\[2)\ \left( 5ab^{2} - 14a^{2}b^{2} - 3a^{3}b \right)\ :\]
\[:(2ab) = 2,5b - 7ab - 1,5a^{2}\]