Find the equivalent capacitance between `A` and `B`.

Explanation

Charge supplied by battery, enters at `A` and emerges at `B`. Cahrge `Q` is divided into `Q_(1)` and `Q_(2)` appears on `3C` and `6C`, hence they are in series. In the same manner, `Q_(2)` appears on `9C` and `18C`, hence they are in series. capacitances `2C` and `6C` are connected such that one plate of two capacitors at `A` and another plate of capacitors at `B`, hence they are in paralllel.
`C_(eq)=8C`