Answer
Please see the work below.
Work Step by Step
We connect $7.2\mu F$ and $9.0\mu F$ in series to obtain:
$C_{eq_1}=(\frac{1}{7.2\mu F}+\frac{1}{9.0\mu F})^{-1}=4.0\mu F$
Now we connect $C_{eq_1}$ to $18\mu F$ in parallel to obtain the required $22\mu F$ as follows:
$C_{eq}=C_{eq_1}+18\mu F$
$\implies C_{eq}=4.0\mu F+18\mu F$
$C_{eq}=22\mu F$
