Because point C is the point where we first met.
So during the whole journey, A can run 30 kilometers.
Because point D is the point of the second meeting, it took 2×2- 1=3 times for the second meeting.
30× 3 = 90 straight line
Suppose the whole journey is x kilometers.
Then BD=x-AD=x-40.
90=x+x-40
130=2x
x=65
BD=65-40=25
BC = 25+CD = 25+(40-30)= 35(B's way)
So speed A: speed B =30:35=6:7.
Let the speed of vehicle A and vehicle B be V 1, and the distance between V2 and AB be x kilometers, from the meaning of the question:
30/v 1=(x-30)/v2,( 1)(30+40)/v2 =(x-30+x-40)/v 1,(2)
(1) is reduced to 30/(x-30)=v 1/v2.
(2) Simplified to 70/(2x-70)=v2/v 1,
The phase of the two formulas * cancels V 1, and V2 is: 2100/[(x-30 (* (2x-70)] =1.
2 100=(x-30)*(2x-70)=2x^2- 130x+2 100
x=65
v 1/v2 = 30/(65-30)= 30/35 = 6/7
That is, AB is 65 kilometers apart, and the speed ratio of A to B is 6:7.
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