A crew can row a certain course up the stream in 84 minutes; they can row the same course down stream in 6 minutes less than they can row it in still water. How long would they take to row down with the stream	Pick one:	A) 45 or 23 minutes	B) 63 or 12 minutes	C) 78 minutes	D) 19 minutes	E) 25 minutes
A method has been discussed here to nullify the calculations though.   All I can input here is,   speed of a crew in still water = 1/2 ( speed upstream + speed downstream)   approximating this for time,   t = 1/2(84+ (t-6))   giving t = 78   78 minutes.
<result>C</result>
A crew can row a certain course up the stream in 84 minutes; they can row the same course down stream in 6 minutes less than they can row it in still water. How long would they take to row down with the stream