1. **State the problem:** Solve the equation $19 + X = 29$ for $X$. 2. **Formula and rules:** To solve for $X$, isolate $X$ on one side of the equation by performing inverse operations. 3. **Step-by-step solution:** - Subtract 19 from both sides: $19 + X - 19 = 29 - 19$ - Simplify: $X = 10$ 4. **Explanation:** We moved the constant term 19 to the right side by subtracting it from both sides, leaving $X$ alone on the left side. The result is $X = 10$. **Final answer:** $X = 10$