Question 742418
 Let the speed of paddling in still waters be {{{x}}} mph and speed of current be {{{y}}} mph

DOWNSTREAM
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if {{{Distance=12mil}}} and  {{{time=2h}}}, then


{{{Speed =(x+y)mph = Distance / time = 12 /2 = 6}}}


{{{x+ y = 6 }}}...... eq.1


UPSTREAM
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{{{Speed = (x-y) mph = Distance / time = 12/6 = 2}}}


{{{x -y = 2}}}...... eq.2


eq.1 + eq.2


{{{x+6+x-6 =6+2}}}


{{{2x =8}}}


{{{x = 4mph}}}, then


{{{4mph+ y = 6mph }}}


{{{y = 2mph}}}........ ANSWER


CHECK


{{{12 / (4+2) = 2 hours}}}


{{{12 / ( 4-2) = 6 hours}}}