1. **State the problem:** Simplify the expression $4\sqrt{10} - 2\sqrt{10}$. 2. **Recall the rule:** When subtracting terms with the same radical part, you can subtract the coefficients directly. 3. **Apply the rule:** Both terms have $\sqrt{10}$, so subtract the coefficients: $$4\sqrt{10} - 2\sqrt{10} = (4 - 2)\sqrt{10}$$ 4. **Simplify the coefficients:** $$4 - 2 = 2$$ 5. **Write the final simplified expression:** $$2\sqrt{10}$$ This is the simplified form of the given expression.