In this example we are multiplying two binomials so FOIL method can be used.
$$ \begin{aligned} \left( \color{blue}{ 4x-3}\right) \cdot \left( \color{orangered}{ x+6}\right) &= \underbrace{ \color{blue}{4x} \cdot \color{orangered}{x} }_{\text{FIRST}} + \underbrace{ \color{blue}{4x} \cdot \color{orangered}{6} }_{\text{OUTER}} + \underbrace{ \left( \color{blue}{-3} \right) \cdot \color{orangered}{x} }_{\text{INNER}} + \underbrace{ \left( \color{blue}{-3} \right) \cdot \color{orangered}{6} }_{\text{LAST}} = \\ &= 4x^2 + 24x + \left( -3x\right) + \left( -18\right) = \\ &= 4x^2 + 24x + \left( -3x\right) + \left( -18\right) = \\ &= 4x^2+21x-18; \end{aligned} $$