Step 1: First we have to write polynomials in descending order.

$$ \begin{aligned} P(x) &= 18a+8 \\ Q(x) &= 46a+9 \\ \end{aligned} $$

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

$$ \begin{aligned} \left( \color{blue}{ 18a+8}\right) \cdot \left( \color{orangered}{ 46a+9}\right) &= \underbrace{ \color{blue}{18a} \cdot \color{orangered}{46a} }_{\text{FIRST}} + \underbrace{ \color{blue}{18a} \cdot \color{orangered}{9} }_{\text{OUTER}} + \underbrace{ \color{blue}{8} \cdot \color{orangered}{46a} }_{\text{INNER}} + \underbrace{ \color{blue}{8} \cdot \color{orangered}{9} }_{\text{LAST}} = \\ &= 828a^2 + 162a + 368a + 72 = \\ &= 828a^2 + 162a + 368a + 72 = \\ &= 828a^2+530a+72; \end{aligned} $$

Polynomial Operations Calculator