The problem you have uploaded is:

$-6 - (-9)$

To solve this:

1. The subtraction of a negative number becomes an addition, so: $-6 - (-9) = -6 + 9$

2. Now, add $-6$ and $9$: $-6 + 9 = 3$

The answer is: $\boxed{3}$

Would you like more details or have any questions about this?

Here are 5 related questions for practice:

1. What is $-7 - (-5)$?
2. Calculate $8 - (-3)$.
3. What is the result of $-10 - (-12)$?
4. Solve $-3 + (-4)$.
5. What is $5 - (-2)$?

Tip: When subtracting a negative number, it becomes addition. Always remember, $-(-a) = +a$.