\[x \cdot (x - 3)(4 - x) =\]
\[= 16 - x \cdot (x - 3,5)^{2}\]
\[\left( x^{2} - 3x \right)(4 - x) =\]
\[= 16 - x^{3} + 7x^{2} - 12,25x\]
\[0,25x = 16\]
\[x = 64\]
\[Ответ:x = 64.\]