Question

The first buses to X and Y leave a bus station at 7 am
Buses to X leave every 25 minutes.
Buses to Y leave every 20 minutes.
When will the buses to X and Y next leave at the same time

Answer 1

The lowest common multiple of 25 and 20 is 100
The next time the buses leave at the same time is 100 minutes after 7 am which is 8:40 am