Two cars, 100 kilometers apart, start driving toward each other. The black car drives west at a speed of forty kilometers per hour and the white car at a speed of sixty kilometers per hour. A bird starts from the same spot as the white car and flies at a speed of 80 kilometers per hour. When the bird reaches the black car, it turns and flies back toward the white car, whereupon it turns and flies back again to the black car. This continues until the cars meet.
How far has the bird traveled at the moment when the two cars pass each other?
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