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

$$ \begin{aligned} \left( \color{blue}{ 4x-9}\right) \cdot \left( \color{orangered}{ 7x+4}\right) &= \underbrace{ \color{blue}{4x} \cdot \color{orangered}{7x} }_{\text{FIRST}} + \underbrace{ \color{blue}{4x} \cdot \color{orangered}{4} }_{\text{OUTER}} + \underbrace{ \left( \color{blue}{-9} \right) \cdot \color{orangered}{7x} }_{\text{INNER}} + \underbrace{ \left( \color{blue}{-9} \right) \cdot \color{orangered}{4} }_{\text{LAST}} = \\ &= 28x^2 + 16x + \left( -63x\right) + \left( -36\right) = \\ &= 28x^2 + 16x + \left( -63x\right) + \left( -36\right) = \\ &= 28x^2-47x-36; \end{aligned} $$

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