Using superposition, find $V_o$ in the circuit shown given that $I_3 = 3 mA, V_1 = 2 V, V_2 = 10 V, R_1 = 10 k\Omega , R_2 = 12 k\Omega, R_3 = 7 k\Omega, R_4 = 3 k\Omega$ and $R_5 = 9 k\Omega.$

With just $V_1$ turned on, $V_o =$ $V$
With just $V_2$ turned on, $V_o =$ $V$
With just $I_3$ turned on, $V_o =$ $V$
$V_o =$ $V$