Combine like terms:

$$ \color{blue}{2x} + \color{blue}{9x} = \color{blue}{11x} $$

Multiply $ \dfrac{18}{x} $ by $ 2 $ to get $ \dfrac{ 36 }{ x } $.

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

Step 2: Multiply numerators and denominators.

Step 3: Simplify numerator and denominator.

$$ \begin{aligned} \frac{18}{x} \cdot 2 & \xlongequal{\text{Step 1}} \frac{18}{x} \cdot \frac{2}{\color{red}{1}} \xlongequal{\text{Step 2}} \frac{ 18 \cdot 2 }{ x \cdot 1 } = \\[1ex] & \xlongequal{\text{Step 3}} \frac{ 36 }{ x } \end{aligned} $$

Add $11x$ and $ \dfrac{36}{x} $ to get $ \dfrac{ \color{purple}{ 11x^2+36 } }{ x }$.

Step 1: Write $ 11x $ as a fraction by putting $ \color{red}{ 1 } $ in the denominator.

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

$$ \begin{aligned} 11x+ \frac{36}{x} & \xlongequal{\text{Step 1}} \frac{11x}{\color{red}{1}} + \frac{36}{x} = \frac{ 11x \cdot \color{blue}{ x }}{ 1 \cdot \color{blue}{ x }} + \frac{ 36 }{ x } = \\[1ex] & \xlongequal{\text{Step 2}} \frac{ \color{purple}{ 11x^2 } }{ x } + \frac{ \color{purple}{ 36 } }{ x }=\frac{ \color{purple}{ 11x^2+36 } }{ x } \end{aligned} $$

Add $ \dfrac{11x^2+36}{x} $ and $ 12x $ to get $ \dfrac{ \color{purple}{ 23x^2+36 } }{ x }$.

Step 1: Write $ 12x $ as a fraction by putting $ \color{red}{ 1 } $ in the denominator.

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

$$ \begin{aligned} \frac{11x^2+36}{x} +12x & \xlongequal{\text{Step 1}} \frac{11x^2+36}{x} + \frac{12x}{\color{red}{1}} = \frac{ 11x^2+36 }{ x } + \frac{ 12x \cdot \color{blue}{ x }}{ 1 \cdot \color{blue}{ x }} = \\[1ex] & \xlongequal{\text{Step 2}} \frac{ \color{purple}{ 11x^2+36 } }{ x } + \frac{ \color{purple}{ 12x^2 } }{ x }=\frac{ \color{purple}{ 23x^2+36 } }{ x } \end{aligned} $$

Add $ \dfrac{23x^2+36}{x} $ and $ 36 $ to get $ \dfrac{ \color{purple}{ 23x^2+36x+36 } }{ x }$.

Step 1: Write $ 36 $ as a fraction by putting $ \color{red}{ 1 } $ in the denominator.

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

$$ \begin{aligned} \frac{23x^2+36}{x} +36 & \xlongequal{\text{Step 1}} \frac{23x^2+36}{x} + \frac{36}{\color{red}{1}} = \frac{ 23x^2+36 }{ x } + \frac{ 36 \cdot \color{blue}{ x }}{ 1 \cdot \color{blue}{ x }} = \\[1ex] & \xlongequal{\text{Step 2}} \frac{ \color{purple}{ 23x^2+36 } }{ x } + \frac{ \color{purple}{ 36x } }{ x }=\frac{ \color{purple}{ 23x^2+36x+36 } }{ x } \end{aligned} $$