Finding the Voltage drop across capacitors
This is called a Capacitive Voltage transformer that divides voltages after charging up according to their impedances. 

Normally this used for HVAC with a small initial HV cap to divide down to sense a reduced voltage on a larger cap. But in the case of DC it can work the same as long as we neglect leakage resistance in the steady state.

We know that Zc(ω)=1/(jωC) and that a step function ( turning on the Vdc ) contains a continuous spectrum of frequencies from DC all the way up to 1/RsC but since these are ideal Caps with Rs=0, it does not matter how fast they charge up for the steady-state.

So we just can say here that Zc is proportional to 1/C and use that for doing Thevenin Calculations and voltage dividers just like equivalent R's.

now try again.