\[28 \cdot (x + 6) - 28 \cdot (x - 4) =\]
\[= 5 \cdot (x - 4)(x + 6)\]
\[28x + 168 - 28x + 112 =\]
\[= 5 \cdot \left( x^{2} + 2x - 24 \right)\]
\[280 = 5x^{2} + 10x - 120\]
\[5x^{2} + 10x - 120 - 280 = 0\]
\[5x² + 10x - 400 = 0\ \ \ |\ :5\]
\[x^{2} + 2x - 80 = 0\]
\[x_{1} + x_{2} = - 2;\ \ x_{1} \cdot x_{2} = - 80\]
\[x_{1} = 8,\ \ x_{2} = - 10\]
\[Ответ:\ x = 8;\ x = - 10.\]