To isolate the distance \( d \) in the formula \( t = \frac{d}{v} \), you would need to eliminate the division by \( v \). To do this, the operation you would use is multiplication.
You can isolate \( d \) by multiplying both sides of the equation by \( v \):
\[ d = t \cdot v \]
Therefore, the correct operation to isolate the distance is multiplication.