1. **State the problem:** Given the perimeter of the rhombus VWXY is 20.5 cm, find the length of one side. 2. **Recall the formula for the perimeter of a rhombus:** $$\text{Perimeter} = 4 \times \text{side length}$$ 3. **Set up the equation:** Let the side length be $s$. Then, $$4s = 20.5$$ 4. **Solve for $s$:** $$s = \frac{20.5}{4} = 5.125$$ 5. **Interpretation:** Each side of the rhombus VWXY is 5.125 cm long. **Final answer:** $$\boxed{5.125 \text{ cm}}$$