1. The problem asks us to subtract the numbers: $-6 - (-9)$. 2. Recall the rule: subtracting a negative number is the same as adding its positive counterpart. So, $a - (-b) = a + b$. 3. Applying this rule, we rewrite the expression as: $$-6 - (-9) = -6 + 9$$ 4. Now, add $-6$ and $9$. Since $9$ is positive and $-6$ is negative, subtract the smaller absolute value from the larger absolute value and keep the sign of the larger absolute value. 5. Calculate: $$9 - 6 = 3$$ Since $9$ is positive, the result is positive. 6. Therefore, the final answer is: $$3$$