This problem can be simplified. The hound speed is 22km/h, the hare speed is 18m/h, and the distance is 2km. In this way, it is a simple pursuit problem.

In order to catch the hare, the hounds must chase it for 2 kilometers. It is known that their speed difference is 4 kilometers per hour, so the distance divided by the speed can get the time, and the time is 2 divided by 4=0.5 hours. That was 30 minutes.