For 0 < t < 3 s (when the switch on the right is still closed), consider a Thevenin generator that can replace the voltage source and the two resistors as a way of determining the time constant for discharge of the capacitor.
For t > 3 s, the capacitor continues its discharge with a different time constant through the single 2 ohm resistor after the second switch is opened.
Hint for P7.6
When the switch is open, the current source and two resistors may be replaced with a Thevenin generator to determine the time constant for energization of the inductor.
When the switch is closed, the inductor deenergizes through the two resistors now effectively in parallel.