5s/9-4s/9= 15*5
Solution: s=675
So the distance between a and b is 675 kilometers.
2. The speed of A is 440/6=220/3 (km/h) and the speed of B is 440/5=88 (km/h).
T = (440-220/3 *1)/(220/3+88) = 25/1(hour).
So when two cars meet, the distance between A and B is also S = 88 * 25/11= 200 (km).
3. Let A and B do V A and V B every minute, and get the following equation:
(V A +V B) *5=540,V A: V B =5:4。
Solution: V A =60 (km/min), V B =48 (km/min).