Multiply $18$ by $ \dfrac{q^4}{p^5} $ to get $ \dfrac{ 18q^4 }{ p^5 } $.

Step 1: Write $ 18 $ as a fraction by putting $ \color{red}{1} $ in the denominator.

Step 2: Multiply numerators and denominators.

Step 3: Simplify numerator and denominator.

$$ \begin{aligned} 18 \cdot \frac{q^4}{p^5} & \xlongequal{\text{Step 1}} \frac{18}{\color{red}{1}} \cdot \frac{q^4}{p^5} \xlongequal{\text{Step 2}} \frac{ 18 \cdot q^4 }{ 1 \cdot p^5 } = \\[1ex] & \xlongequal{\text{Step 3}} \frac{ 18q^4 }{ p^5 } \end{aligned} $$

Multiply $27$ by $ \dfrac{p^9}{q^7} $ to get $ \dfrac{ 27p^9 }{ q^7 } $.

Step 1: Write $ 27 $ as a fraction by putting $ \color{red}{1} $ in the denominator.

Step 2: Multiply numerators and denominators.

Step 3: Simplify numerator and denominator.

$$ \begin{aligned} 27 \cdot \frac{p^9}{q^7} & \xlongequal{\text{Step 1}} \frac{27}{\color{red}{1}} \cdot \frac{p^9}{q^7} \xlongequal{\text{Step 2}} \frac{ 27 \cdot p^9 }{ 1 \cdot q^7 } = \\[1ex] & \xlongequal{\text{Step 3}} \frac{ 27p^9 }{ q^7 } \end{aligned} $$

Multiply $ \dfrac{18q^4}{p^5} $ by $ \dfrac{27p^9}{q^7} $ to get $ \dfrac{ 486p^9q^4 }{ p^5q^7 } $.

Step 1: Multiply numerators and denominators.

Step 2: Simplify numerator and denominator.

$$ \begin{aligned} \frac{18q^4}{p^5} \cdot \frac{27p^9}{q^7} & \xlongequal{\text{Step 1}} \frac{ 18q^4 \cdot 27p^9 }{ p^5 \cdot q^7 } \xlongequal{\text{Step 2}} \frac{ 486p^9q^4 }{ p^5q^7 } \end{aligned} $$