The expression $-9 + 6$ simplifies to:

$-9 + 6 = -3$

So, the answer is $-3$.

Would you like more details or have any questions?

Here are some related questions:

1. What is the result of $-12 + 8$?
2. How do you add two negative numbers?
3. What is the absolute value of $-9$?
4. How does subtracting a negative number differ from adding a positive number?
5. What happens when you add a positive number to a larger negative number?

Tip: When adding a positive number to a negative number, subtract the smaller absolute value from the larger one, and keep the sign of the number with the larger absolute value.