Use Thévenin's and Norton's Theorems to find $V_0$ in the circuit shown in the figure below, given that $R_1 = 2.00k\Omega$, $R_2 = 4.00k\Omega$, $R_3 = 2.00k\Omega$, $R_4 = 6.00k\Omega$, $V_1 = 6.00V$, and $I_1 = 2.00mA$.
$V_1$
$R_1$
$R_2$
$I_1$
$R_3$
$R_4$
$V_0$