Question 162661
{{{s}}}= speed in still water
{{{c}}}= speed of current
{{{9 = (s + c)*3}}}
{{{9 = (s - c)*9}}}
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(1) {{{9 = 3s + 3c}}}
(2) {{{9 = 9s - 9c}}}
Divide both sides of (2) by {{{3}}} and add it to (1)
(1) {{{9 = 3s + 3c}}}
(2) {{{3 = 3s - 3c}}}
{{{12 = 6s}}}
{{{s = 2}}} km/hr
(1) {{{3 = 3*2 - 3c}}}
{{{-3 = -3c}}}
{{{c = 1}}}km/hr
The speed of the boat in still water is 2 km/hr
The speed of the current is 1 km/hr