1. **Problem:** Find the length of segment CD given the expressions for its parts: $2x + 4$ and $4x$. 2. **Formula and rules:** Since CD is divided into two parts, the total length of CD is the sum of these parts: $$\text{CD} = (2x + 4) + 4x$$ 3. **Intermediate work:** Combine like terms: $$2x + 4 + 4x = 6x + 4$$ 4. **Explanation:** To find the length of CD, we add the two segments together because they form the whole segment CD. 5. **Final answer:** The length of CD is $$6x + 4$$ units. Note: Since no value for $x$ is given, the answer is expressed in terms of $x$.