A 4.0-mF capacitor is charged to 6.0-V. It is then connected in series with a 3.0-MW resistor and connected to a 12-V battery. How long after being connected to the battery will the voltage across the capacitor be 9.0 V?

Kirchhoff's junction rule: At any junction point, the sum of all the currents entering the junction must equal the sum of all the currents leaving the junction.
Kirchhoff's loop rule: The sum of the changes in potential around any closed path of a circuit must be zero.