From the above circuit diagram, the equivalent capacitance of the combination of capacitors is,
Ceq=C1+C2C3C2C3,
Ceq=2+6+126×12=6μF
Then, QC2QC1=C2+C3C2C3VC1V=6×122×(6+12)=21
and QC2=QC3
So, the ratio of charges are, 1:2:2.