1. **State the problem:** We need to find the value of $p$ in parallelogram UVWX where side $UV = 2p$ and side $WX = p + 12$. 2. **Recall the property of parallelograms:** Opposite sides of a parallelogram are equal in length. Therefore, $UV = WX$. 3. **Set up the equation:** $$2p = p + 12$$ 4. **Solve for $p$:** Subtract $p$ from both sides: $$2p - \cancel{p} = \cancel{p} + 12 - p$$ $$p = 12$$ 5. **Conclusion:** The value of $p$ is 12.