Question

two bus start from the same bus stand at 8a.m. one travels at 40km/h and other at 50km/h. the second bus reaches the next stop at 10a.m.How much later will the first bus arrive?

Answer 1

distance covered=50km/hr*2hrs=100km

time for slow bus:
time=100km/40km/hr=2.5hr
so it will arrive 30 min later

Answer 2

2 hrs at 50km/hr = 100 km

So, how long does it take to go that far at 40 km/hr?

Answer 3

How 2.5 hr becomes 30 min? Can anyone explain it?