In this example we are multiplying two binomials so FOIL method can be used.

$$ \begin{aligned} \left( \color{blue}{ 3x-3}\right) \cdot \left( \color{orangered}{ -3x-6}\right) &= \underbrace{ \color{blue}{3x} \cdot \left( \color{orangered}{-3x} \right) }_{\text{FIRST}} + \underbrace{ \color{blue}{3x} \cdot \left( \color{orangered}{-6} \right) }_{\text{OUTER}} + \underbrace{ \left( \color{blue}{-3} \right) \cdot \left( \color{orangered}{-3x} \right) }_{\text{INNER}} + \underbrace{ \left( \color{blue}{-3} \right) \cdot \left( \color{orangered}{-6} \right) }_{\text{LAST}} = \\ &= -9x^2 + \left( -18x\right) + 9x + 18 = \\ &= -9x^2 + \left( -18x\right) + 9x + 18 = \\ &= -9x^2-9x+18; \end{aligned} $$

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