To find out how many slices of the cherry pie Quinten and his friends ate, we first need to determine the fraction of the peach pie that they consumed.
Quinten and his friends ate \( \frac{6}{12} \) of the peach pie, which simplifies to \( \frac{1}{2} \).
Since they ate the same fraction of the cherry pie, we need to find \( \frac{1}{2} \) of the cherry pie.
The cherry pie has 8 slices, so:
\[ \frac{1}{2} \times 8 = 4 \]
Thus, they ate 4 slices of the cherry pie.
The correct answer is: 4.