According to the meaning of the question, the speed of car B = 105/2.5=42 (km/h), and the speed of car A = (a-105)/2.5 = 0.4a-42 (km/h).
Then: (A+90)/42=(2A-90)/(0.4A-42), and the solution is: A=225 (km).
A:
The distance between ab is 225 kilometers.