Henry Ernest Dudeney/Modern Puzzles/33 - A Rowing Puzzle

by : $33$

 * A Rowing Puzzle
 * A crew can row a certain course upstream in $8 \tfrac 4 7$ minutes,
 * and, if there were no stream, they could row it in $7$ minutes less than it takes them to drift down the stream.


 * How long would it take to row down with the stream?