Step 1: First we have to write polynomials in descending order.
$$ \begin{aligned} P(x) &= -6x+1 \\ Q(x) &= 4x+9 \\ \end{aligned} $$In this example we are multiplying two binomials so FOIL method can be used.
$$ \begin{aligned} \left( \color{blue}{ -6x+1}\right) \cdot \left( \color{orangered}{ 4x+9}\right) &= \underbrace{ \left( \color{blue}{-6x} \right) \cdot \color{orangered}{4x} }_{\text{FIRST}} + \underbrace{ \left( \color{blue}{-6x} \right) \cdot \color{orangered}{9} }_{\text{OUTER}} + \underbrace{ \color{blue}{1} \cdot \color{orangered}{4x} }_{\text{INNER}} + \underbrace{ \color{blue}{1} \cdot \color{orangered}{9} }_{\text{LAST}} = \\ &= -24x^2 + \left( -54x\right) + 4x + 9 = \\ &= -24x^2 + \left( -54x\right) + 4x + 9 = \\ &= -24x^2-50x+9; \end{aligned} $$