Subtract $ \dfrac{5}{q} $ from $ 9 $ to get $ \dfrac{ \color{purple}{ 9q-5 } }{ q }$.

Step 1: Write $ 9 $ 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 first fraction by $\color{blue}{ q }$.

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