Use the distributive property.

Subtract $1$ from $ \dfrac{1}{4} $ to get $ \dfrac{ \color{purple}{ -3 } }{ 4 }$.

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

Step 2: To subtract fractions they must have the same denominator.
We can create a common denominator by multiplying the second fraction by $\color{blue}{4}$.

$$ \begin{aligned} \frac{1}{4} -1 & \xlongequal{\text{Step 1}} \frac{1}{4} - \frac{1}{\color{red}{1}} = \frac{ 1 }{ 4 } - \frac{ 1 \cdot \color{blue}{ 4 }}{ 1 \cdot \color{blue}{ 4 }} = \\[1ex] & \xlongequal{\text{Step 2}} \frac{ \color{purple}{ 1 } }{ 4 } - \frac{ \color{purple}{ 4 } }{ 4 }=\frac{ \color{purple}{ -3 } }{ 4 } \end{aligned} $$

Multiply $ \dfrac{-3}{4} $ by $ x $ to get $ \dfrac{ -3x }{ 4 } $.

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

Step 2: Multiply numerators and denominators.

Step 3: Simplify numerator and denominator.

$$ \begin{aligned} \frac{-3}{4} \cdot x & \xlongequal{\text{Step 1}} \frac{-3}{4} \cdot \frac{x}{\color{red}{1}} \xlongequal{\text{Step 2}} \frac{ \left( -3 \right) \cdot x }{ 4 \cdot 1 } = \\[1ex] & \xlongequal{\text{Step 3}} \frac{ -3x }{ 4 } \end{aligned} $$