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Một ca nô chuyển động đều trên dòng sông.Vận tốc của ca no khi xuôi dòng là 22km/h và khi ngược dòng là 18km/h. a/Nếu ca nô không nổ máy thì quãng đường mà nó trôi theo dòng nước trong vòng 15p là bao nhiêu? b/Gỉa sử mặt nước yên tĩnh, ca nô nổ máy thì vận tốc của nó lúc đó là bao nhiêu?
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