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

Step 1: Write $ 4 $ as a fraction by putting $ \color{red}{1} $ in the denominator.

Step 2: Multiply numerators and denominators.

Step 3: Simplify numerator and denominator.

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

Multiply $ \dfrac{4h^5}{18} $ by $ h^2 $ to get $ \dfrac{ 4h^7 }{ 18 } $.

Step 1: Write $ h^2 $ as a fraction by putting $ \color{red}{ 1 } $ in the denominator.

Step 2: Multiply numerators and denominators.

Step 3: Simplify numerator and denominator.

$$ \begin{aligned} \frac{4h^5}{18} \cdot h^2 & \xlongequal{\text{Step 1}} \frac{4h^5}{18} \cdot \frac{h^2}{\color{red}{1}} \xlongequal{\text{Step 2}} \frac{ 4h^5 \cdot h^2 }{ 18 \cdot 1 } = \\[1ex] & \xlongequal{\text{Step 3}} \frac{ 4h^7 }{ 18 } \end{aligned} $$

Multiply $ \dfrac{4h^7}{18} $ by $ u^3 $ to get $ \dfrac{ 4h^7u^3 }{ 18 } $.

Step 1: Write $ u^3 $ as a fraction by putting $ \color{red}{ 1 } $ in the denominator.

Step 2: Multiply numerators and denominators.

Step 3: Simplify numerator and denominator.

$$ \begin{aligned} \frac{4h^7}{18} \cdot u^3 & \xlongequal{\text{Step 1}} \frac{4h^7}{18} \cdot \frac{u^3}{\color{red}{1}} \xlongequal{\text{Step 2}} \frac{ 4h^7 \cdot u^3 }{ 18 \cdot 1 } = \\[1ex] & \xlongequal{\text{Step 3}} \frac{ 4h^7u^3 }{ 18 } \end{aligned} $$