Question 957182
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A cruise ship can sail 25 mph in calm water. Sailing with the Gulf Stream, the ship can sail 256 mi 
in the same amount of time it takes to sail 144 mi against the Gulf Stream. Find the rate of the Gulf Stream.
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        Calculations in the post by @lwsshak3 are incorrect due to arithmetic error.

        His answer "25 mph" for the Gulf Stream rate is absurdist,

        since then the cruise ship could not sail against the current.


        I came to bring a correct solution.



let c = rate of gulf stream
25+c = rate of ship sailing with Gulf Stream
25-c = rate of ship sailing against Gulf Stream
travel time=distance/rate (same in both directions)
...
{{{256/(25+c) = 144/(25-c)}}}
..
256(25-c) = 144(25+c)
6400 - 256c = 3600 + 144c
400c = 2800
c = 2800/400 = 7
rate of gulf stream = 7 mph


Solved correctly.