We can use distribution property to multiply the polynomial by the monomial.
$$ \begin{aligned} \color{blue}{-4x} \cdot \left( x^2+6x-7 \right) &= \color{blue}{-4x} \cdot x^2 + \color{blue}{-4x} \cdot 6x + \color{blue}{-4x} \cdot \left( -7\right) = \\ &= -4x^3-24x^2+28x \end{aligned} $$