Jack can row at 7 kmph and still water. He takes 7/2 hours to row from A to B and back. What is the distance between A and B if the speed of the stream is 3 kmph?  Choose the correct choice from the following choices:	A) 12 km	B) 20 km	C) 18 km	D) 14 km	E) 10 km
Let the distance between A and B be x km.   Total time = x/(7 + 3) + x/(7 - 3) = 7/2   =&gt; x/10 + x/4 = 7/2 =&gt; (5x + 2x)/20 = 7/2 =&gt; x = 10 km.   ANSW10 kmR:10 km
<result>E</result>
Jack can row at 7 kmph and still water. He takes 7/2 hours to row from A to B and back. What is the distance between A and B if the speed of the stream is 3 kmph?