Question: If $k - 3 - 9 = 12$, what is the value of $k$?
1. **State the problem:** We need to find the value of $k$ in the equation $k - 3 - 9 = 12$.
2. **Combine like terms:** Simplify the left side by combining $-3$ and $-9$:
$$k - 3 - 9 = k - (3 + 9) = k - 12$$
So the equation becomes:
$$k - 12 = 12$$
3. **Isolate $k$:** To solve for $k$, add $12$ to both sides:
$$k - 12 + 12 = 12 + 12$$
This simplifies to:
$$k = 24$$
4. **Final answer:** The value of $k$ is $24$.