Simplification of the expression is given below:
[tex]\begin{gathered} =(x(5x+7)-6(5x+7))-(3x^2(x-1)-4x(x-1)+8(x-1)) \\ =(5x^2+7x-30x-42)-(3x^3-3x^2-4x^2+4x+8x-8) \\ =(5x^2-23x-42)-(3x^3-7x^2+12x-8) \\ =5x^2-23x-42-3x^3+7x^2-12x+8 \\ =-3x^3+12x^2-35x-34 \end{gathered}[/tex]
