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trinh0908137826
2 năm trước
Hai chiếc tàu xuất phát cùng một lúc và đi ngược chiều nhau trên khúc sông AB. Biết vận tốc riêng của tàu đi xuôi dòng từ A đến B là 35 (km/h) còn vận tốc riêng của tàu đi ngược dòng từ B về A là 40 (km/h). Hai tàu gặp nhau sau 90 (phút) rời bến. Biết tàu đi từ B có nghỉ 45 (phút) do gặp sự cố và khúc sông AB dài 84 (km). Tính vận tốc dòng nước
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