Question 318786
Rate*Time=Distance
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Let C be the current speed.
1.{{{(24+C)t=150}}}
2.{{{(24-C)t=90}}}
From eq. 1 and eq. 2,
{{{t=150/(24+C)=90/(24-C)}}}
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{{{150(24-C)=90(24+C)}}}
{{{360-15C=216+9C}}}
{{{24C=144}}}
{{{highlight(C=6)}}}
The speed of the current is 6 km/h.