In the circuit shown, the energy stored in $1\mu F$ capacitor is 

Equivalent of $5\mu F$ and  $1\mu F$ is $6\mu F$ .
The potential difference across  $3\mu F$ and $6\mu F$  in series is 24 V. potential difference across $6\mu F$ is  $\frac{3}{3+6}\times 24=8V$
∴ energy in $1\mu F$  capacitor is  $=\frac{1}{2}C{V}^2$
$=\frac{1}{2}\times 1\times 8^2=32\mu J$