1. **State the problem:** Simplify the expression $10x^2 - 8x^2$. 2. **Recall the rule:** When subtracting like terms, subtract their coefficients and keep the variable part unchanged. 3. **Apply the rule:** $$10x^2 - 8x^2 = (10 - 8)x^2$$ 4. **Simplify the coefficients:** $$= 2x^2$$ 5. **Final answer:** The simplified expression is $2x^2$.