a man can row 20 kmph in still water.it takes him thrice as long to row up as to row down the river.find the rate of stream  Choose the correct answer:  A) 13 km/hr.  B) 6 km/hr.  C) 9 km/hr.  D) 15 km/hr.  E) 10 km/hr.
Let manâ€™s rate upstream be x kmph.then ,his rate downstream=3xkmph.   So,2x=20 or x=10.   Rate upstream=10 km/hr,rate downstream=30 km/hr.   Hence,rate of stream=1/2(30-10)km/hr=10 km/hr.   Answer is 10 km/hr..
<result>E</result>
a man can row 20 kmph in still water.it takes him thrice as long to row up as to row down the river.find the rate of stream