In this example we are multiplying two binomials so FOIL method can be used.
$$ \begin{aligned} \left( \color{blue}{ x-9}\right) \cdot \left( \color{orangered}{ x+3}\right) &= \underbrace{ \color{blue}{x} \cdot \color{orangered}{x} }_{\text{FIRST}} + \underbrace{ \color{blue}{x} \cdot \color{orangered}{3} }_{\text{OUTER}} + \underbrace{ \left( \color{blue}{-9} \right) \cdot \color{orangered}{x} }_{\text{INNER}} + \underbrace{ \left( \color{blue}{-9} \right) \cdot \color{orangered}{3} }_{\text{LAST}} = \\ &= x^2 + 3x + \left( -9x\right) + \left( -27\right) = \\ &= x^2 + 3x + \left( -9x\right) + \left( -27\right) = \\ &= x^2-6x-27; \end{aligned} $$