① Two vans left AB relatively at the same time and met in 4.5 hours. When they met, the bus was 27 kilometers longer than the truck, and the speed of the truck was 4/5 of that of the bus. What's the distance between AB and AB?

Solution: The bus runs more than the truck every hour: 27/4.5 = 6 km/h.

AB the distance between the two places:

6/(5-4)*(5+4)*4.5

=54*4.5

= 243 km

(2) Two ships leave from Port A and Port B relatively simultaneously. The speed of passenger ships is 42 kilometers per hour, and the speed of cargo ships is 5/6 of that of passenger ships. Two ships meet at the midpoint of port A and port B 7 kilometers. What is the distance between port A and port B?

Solution: cargo speed: 42 * 5/6 = 35 km/h.

The distance between port a and port b is:

7*2/(42-35)*(42+35)

=2*77

= 154km。