1. The problem is to evaluate the expression $2 - (-9)$. 2. The formula to subtract a negative number is: $a - (-b) = a + b$. This is because subtracting a negative is the same as adding the positive. 3. Applying this rule, we rewrite $2 - (-9)$ as $2 + 9$. 4. Now, add the numbers: $2 + 9 = 11$. 5. Therefore, the final answer is $11$.