\[(5x - 8)(3x + 5) =\]
\[= (14x + 12)(x - 1)\]
\[15x^{2} + 25x - 24x - 40 =\]
\[= 14x^{2} - 14x + 12x - 12\]
\[x^{2} + 3x - 28 = 0\]
\[x_{1} + x_{2} = - 3;\ \ \ \ x_{1} \cdot x_{2} = - 28\]
\[x_{1} = 4,\ \ x_{2} = - 7\]
\[Ответ:x = 4;\ x = - 7.\]