Answer: $4$

Explanation:1. Given Function: The function g is defined by $g(x) = 3x$.

2. Given Condition: We need to find the value of $x$ for which $g(x) = 12$.

3. Set up the Equation: Since $g(x) = 3x$ and $g(x) = 12$, we can set these equal: $3x = 12$

4. Solve for x: Divide both sides of the equation by $3$: $x = \dfrac{12}{3}$ $x = 4$

5. Verify the Solution (Optional): If $x=4$, then $g(4) = 3(4) = 12$. This matches the condition.

6. Conclusion: The value of $x$ for which $g(x)=12$ is $4$.