The distance between Town A and Town B is 450km. Guy A travels from Town A to B at the speed of 80km/h; while Guy B travels from Town B to Town A at the speed of 70km/h. When will Guy A and Guy B meet, if both of them started at the same time?
I don't really understand where to start with. Help!
They meet after $t$ hours, where $80t+70t=450$, that is $t=3$.