Missing detail in the text: total voltage of the circuit 
Missing figure: https://www.physicsforums.com/attachments/prob-24-68-jpg.190851/
Solution:
1) The energy stored in a circuit of capacitors is given by
where
is the equivalent capacitance of the circuit. We can find the value for by using 
and the energy of the system, 
2) Then, let's calculate the equivalente capacitance of C1 and C2. The two capacitors are in series, so their equivalente capacitance is given by
from which we find
3) Then let's find
, the equivalent capacitance of 
and C3. is in series with C4, therefore we can write
Since we already know
and 
, we find
4) Finally, we can find
, because it is in parallel with , and the equivalent capacitance of the two must be equal to :
So, using and , we find
Missing figure: https://www.physicsforums.com/attachments/prob-24-68-jpg.190851/
Solution:
1) The energy stored in a circuit of capacitors is given by
where
2) Then, let's calculate the equivalente capacitance of C1 and C2. The two capacitors are in series, so their equivalente capacitance is given by
from which we find
3) Then let's find
Since we already know
4) Finally, we can find
So, using