1. **State the problem:** Simplify the expression $3 - (-2 + 1) - (-7)$. 2. **Evaluate inside the parentheses:** Calculate $-2 + 1 = -1$. So the expression becomes $3 - (-1) - (-7)$. 3. **Apply the rule for subtracting negatives:** Subtracting a negative is the same as adding the positive. So $3 - (-1) = 3 + 1$ and $- (-7) = +7$. The expression is now $3 + 1 + 7$. 4. **Add the numbers:** $3 + 1 = 4$, then $4 + 7 = 11$. 5. **Final answer:** The simplified value is $11$.