1. **State the problem:** Simplify the expression $8x - 13x - 3$. 2. **Identify like terms:** The terms $8x$ and $-13x$ are like terms because they both contain the variable $x$. 3. **Combine like terms:** $$8x - 13x = (8 - 13)x = -5x$$ 4. **Rewrite the expression:** $$-5x - 3$$ 5. **Final answer:** The simplified expression is $-5x - 3$. This means you subtract the coefficients of $x$ and keep the constant term as is.