Let's simplify the expression step by step.
Starting with:
\[ 3x + 12 \]
We can factor out the common factor of 3 from both terms:
\[ 3(x + 4) \]
So your equation simplifies to:
\[ 3(x + 4) \]
Now you're asking for further simplification. You have the expression \(3(x + 4)\).
If you want to distribute the 3 back:
\[ = 3x + 12 \]
If you're looking to evaluate or relate this to something else, please provide more context!