Question

Bus A and Bus B leave the bus depot at 7 am.
Bus A takes 30 minutes to do its route and bus B takes 50 minutes to complete its route.
At what time are they both back at the bus depot together?
Give your answer as a 12-hour clock time.

Answer 1

maybe around 8 or something like that

Answer 2

Bus A will arrive back at the depot at 7:30, 8:00, 8:30, 9:00, 9:30… you can see the pattern

Bus B will arrive back at the depot at 7:50, 8:40, 9:30… you can see the pattern

you can write a formula but if you just want the first time there back it’s easy to quickly find this in you head.

So 9:30 is the first time they’re back at the same time, assuming they leave the depot right when they get there.