To solve the equation \( \frac{x}{4} = 12 \) using the inverse operation, we need to eliminate the division by 4. The inverse operation of division is multiplication.
So, we multiply both sides of the equation by 4:
\[ x = 12 \times 4 \]
Calculating that gives:
\[ x = 48 \]
Therefore, the correct response is: Inverse operation is multiplication; x = 48.