To solve the equation \(-6x = 48\) for \(x\), you need to isolate \(x\). This can be done by dividing both sides of the equation by \(-6\).
So, the correct operation to perform on both sides of the equation is:
Divide by \(-6\).
Doing this will give you:
\[ x = \frac{48}{-6} = -8 \]
Thus, \(x = -8\).