The steamer going upstream would cover the distance between Town A and Town B in 5 hours. The same steamer going downstream would cover the distance between the towns in 3 hours. How long would it take a raft moving at the speed of the current to float from B to A?	Choose the correct option:  A) 10 hours  B) 12 hours  C) 15 hours  D) 18 hours  E) 20 hours
Let D be the distance, let V be the speed of the steamer, and let x be the speed of the current.   D / (V+x) = 3   D / (V-x) = 5   3V+3x = 5V-5x   V = 4x   D / (4x+x) = 3   D/x = 15 hours   The answer is 15 hours.
<result>C</result>
The steamer going upstream would cover the distance between Town A and Town B in 5 hours. The same steamer going downstream would cover the distance between the towns in 3 hours. How long would it take a raft moving at the speed of the current to float from B to A?