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a b c d

The distance from A to B is 100m, and the distance from B to D is 100m.

From a to c is the distance from the tail to the head of the messenger, and from b to c is the distance from the tail to the head of the messenger.

From C to B is the distance from the beginning to the end of the messenger (because the queue length is 100 m, the queue left when the messenger reached the end 100 m, so when the messenger reached the end, the position of the tail must be the position of the head at the beginning, that is, B), and from C to D is the distance from the beginning to the end of the messenger.

Because the time for the team to walk from B to C is equal to the time for the messenger to walk from A to C, the time for the messenger to walk from C to B is equal to the time for the team to walk from C to D, and because the speed of the messenger and the team is constant and the speed ratio of the messenger and the team is constant, the following formula is established:

Let the distance from b to c be s,

s:( 100+s)=( 100-s):s

s*s= 10000/2

S is about 70.7 (m)

The distance traveled by the messenger is:

100+70.7+70.7 = 241.4 (m)