Question 356149
let x = speed of the river.  Then 14 + x = speed of boat relative to the river DOWNSTREAM, and 14 - x = speed of the boat relative to the river upstream.
Using the formula D = RT, and knowing the fact that the times upstream and downstream are the same, then
{{{6/(14+x) = 3/(14-x)}}},
{{{6(14-x)=3(14+x)}}},
{{{84-6x = 42+3x}}},
{{{42 = 9x}}},
{{{x = 14/3}}}km/hr, the speed of the river.