Question 375231
Rate*Time=Distance
.
.
{{{R*t=D}}}
Let B be the speed of the boat.
With the current,
{{{(B+3)*t=36}}}
{{{t=36/(B+3)}}}
Against the current,
{{{(B-3)*t=24}}}
{{{t=24/(B-3)}}}
Equate the two times,
{{{36/(B+3)=24/(B-3)}}}
{{{36(B-3)=24(B+3)}}}
{{{3(B-3)=2(B+3)}}}
{{{3B-9=2B+6}}}
{{{highlight(B=15)}}}kph