Party A and Party B walk from A to B at the same time. When A has completed the whole journey of 65,438+0 \ 4, B is still 640 meters away from B. When A has completed the remaining 5\6, B has completed the whole journey of 7 \ 65,438+00. What is the distance between AB and b?

Solution: After A left 1/4, the remaining 1- 1/4=3/4.

Then the remaining 5/6 is 3/4×5/6=5/8.

At this time, a * * * left 1/4+5/8=7/8.

Then the distance ratio between Party A and Party B is 7/8: 7/ 10 = 5: 4.

So when A goes 1/4, B goes 1/4×4/5= 1/5.

Then AB distance =640/( 1- 1/5)=800 meters.

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