Let the distance between the two stations A and be x kms.

According to given conditions,

\( \Large \frac{x}{30}-\frac{x}{40} = \left(24 - 15\right) \times \frac{1}{60} \)

\( \Large  \frac{x}{20} = \frac{9}{60} => \frac{x}{120} = \frac{9}{60} \)

\( \Large x = \frac{120 \times 9}{60} = 18 kms \)

Therefore, distance between A and B = 18 km