1. **State the problem:** Simplify the expression $X - 2 - 3X$. 2. **Recall the rules:** When simplifying algebraic expressions, combine like terms. Like terms have the same variable raised to the same power. 3. **Identify like terms:** Here, $X$ and $-3X$ are like terms because both contain the variable $X$. The constant term is $-2$. 4. **Combine like terms:** $$X - 3X = (1 - 3)X = -2X$$ 5. **Rewrite the expression:** $$-2X - 2$$ 6. **Final answer:** The simplified form of the expression is $$-2X - 2$$