A person can row at 9 kmph and still water. He takes 4 1/2 hours to row from A to B and back. What is the distance between A and B if the speed of the stream is 1 kmph? Choose the correct choice from the following answers.
A) 27  B) 22  C) 20  D) 87  E) 23
Let the distance between A and B be x km.   Total time = x/(9 + 1) + x/(9 - 1) = 4.5   =&gt; x/10 + x/8 = 9/2 =&gt; (4x + 5x)/40 = 9/2 =&gt; x = 20 km   Answer: 20
<result>C</result>
A person can row at 9 kmph and still water. He takes 4 1/2 hours to row from A to B and back. What is the distance between A and B if the speed of the stream is 1 kmph?