Stations A and B are 60 km apart on a highway. One truck starts from A and another one from B at the same time. If they travel in the same direction, they meet in 6 hours. But if they travel towards each other, they meet in one hour. The speeds of the two trucks respectively are:
1
45 and 15 km/h
2
40 and 20 km/h
3
35 and 25 km/h
4
30 and 30 km/h