What is the charge stored in each capacitor $C_1$ and $C_2$ in the circuit shown

The current in the circuit

$I=\frac{v}{R_{eff}}=\frac{12}{12}=1A$

PD Across d and c is 12-3x1=9V

$C_{eff}=\frac{c_1{c}_2}{c_1+c_2}=\frac{2}{3}\mu F$

$q=c_{eff}V=\frac{2}{3}\times 9=6\mu C$

Charge on either capacitor is $6\mu C$