Let's solve the equation step by step.
Starting with the equation:
\[ -3x - 9 = -21 \]
- Add 9 to both sides:
\[ -3x = -21 + 9 \]
This simplifies to:
\[ -3x = -12 \]
So, the first blank is -12.
- Divide both sides of the equation by -3:
\[ x = \frac{-12}{-3} \]
This simplifies to:
\[ x = 4 \]
So, the second blank is 4.
Putting it all together:
- The first blank is -12.
- The second blank is 4.
So, the complete solution looks like:
- -3x = -12 (after adding 9)
- x = 4 (after dividing by -3)