A 2.0-F capacitor is charged to a potential difference of 12.0 V. The wires connecting the capacitor

Question:

A 2.0-μF capacitor is charged to a potential difference of 12.0 V. The wires connecting the capacitor to the battery are then disconnected from the battery and connected across a second, initially uncharged, capacitor. The potential difference across the 2.0-μF capacitor then drops to 4 V. What is the capacitance of the second capacitor?