Leila reads 30 chapters of a book in 6 hours.

To find Leila's reading rate in chapters per hour, you can divide the total number of chapters she reads by the total number of hours it takes her to read them.

Leila reads 30 chapters in 6 hours:

\[ \text{Rate} = \frac{\text{Total Chapters}}{\text{Total Hours}} = \frac{30 \text{ chapters}}{6 \text{ hours}} = 5 \text{ chapters per hour} \]

So, Leila's reading rate is 5 chapters per hour.