\(1320-3x^2=74x\)
\(\Leftrightarrow-3x^2-74x+1320=0\)
\(\Leftrightarrow3x^2+74x-1320=0\)
\(\Leftrightarrow3x^2-36x+110x-1320=0\)
\(\Leftrightarrow3x\left(x-12\right)+110\left(x-12\right)=0\)
\(\Leftrightarrow\left(3x+110\right)\left(x-12\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=-\dfrac{110}{3}\\x=12\end{matrix}\right.\)