Multiply $5$ by $ \dfrac{i}{9} $ to get $ \dfrac{ 5i }{ 9 } $.

Step 1: Write $ 5 $ as a fraction by putting $ \color{red}{1} $ in the denominator.

Step 2: Multiply numerators and denominators.

Step 3: Simplify numerator and denominator.

$$ \begin{aligned} 5 \cdot \frac{i}{9} & \xlongequal{\text{Step 1}} \frac{5}{\color{red}{1}} \cdot \frac{i}{9} \xlongequal{\text{Step 2}} \frac{ 5 \cdot i }{ 1 \cdot 9 } \xlongequal{\text{Step 3}} \frac{ 5i }{ 9 } \end{aligned} $$

Subtract $3i$ from $ \dfrac{5i}{9} $ to get $ \dfrac{ \color{purple}{ -22i } }{ 9 }$.

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

Step 2: To subtract raitonal expressions, both fractions must have the same denominator.
We can create a common denominator by multiplying the second fraction by $\color{blue}{9}$.

$$ \begin{aligned} \frac{5i}{9} -3i & \xlongequal{\text{Step 1}} \frac{5i}{9} - \frac{3i}{\color{red}{1}} = \frac{ 5i }{ 9 } - \frac{ 3i \cdot \color{blue}{ 9 }}{ 1 \cdot \color{blue}{ 9 }} = \\[1ex] & \xlongequal{\text{Step 2}} \frac{ \color{purple}{ 5i } }{ 9 } - \frac{ \color{purple}{ 27i } }{ 9 }=\frac{ \color{purple}{ -22i } }{ 9 } \end{aligned} $$