Two cars, A and B, set off from A and B respectively and walked in opposite directions. The speed ratio of A and B is 5:4 at the time of departure. After meeting, A's speed dropped by 20% and B's speed increased by 20%. So, when A arrives at B, B is still 10 kilometers away from A, so how many kilometers is there between A and B?

Solution: It turns out that the speed ratio of A and B is 5:4.

Current A: 5× (1-20%) = 4.

Current B: 4× (1+20%) 4.8.

After A arrives at B, B leaves A: 5-4.8 = 0.2.

Total distance: 10 ÷ 0.2× (4+5) = 450km.