Chiếc xuồng máy chở khách qua sông xuất phát từ bến A đến bờ bên kia 2 bờ sông song song với nhau và dòng sông rộng 800 m. vận tốc của xuồng máy so với dòng nước là 5m/s và vận tốc của dòng nước so với bờ sông là 3m/s.Tính thời gian ngắn nhất mà xuống máy có thể cho khách qua sông.

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