To solve the equation \(-6x = 48\) for \(x\), you should divide both sides of the equation by \(-6\). This will isolate \(x\).
So, the correct operation to perform on both sides of the equation is divide by -6.
Here's how it works:
\[ -6x = 48 \]
Dividing both sides by \(-6\):
\[ x = \frac{48}{-6} = -8 \]