Question 668427
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Hi,
a boat takes 3 hours to travel 30 km down a river, 
then 5 hours to return. how fast is the river flowing?
Note:  D/t = r
 r + c = 10  {{{30km/3hr}}}
<u> r - c = 6</u>   {{{30km/5hr}}}
 2r = 16
  r = 8   and c = 2kmph, how fast the river is flowing