\[3a \cdot 4b^{2} + 6a^{2}b + 6ba \cdot ( - 2b) - 0,2a \cdot 30b =\]
\[= 12ab^{2} + 6a^{2}b - 12ab^{2} - 6ab =\]
\[= 6a^{2}b - 6ab.\]