Question 143699: Rita rows 12km upstream and 12km downstream in 3 hours. The speed of her boat in still water is 9km/hr. Find the speed of the stream Answer by checkley77(12844) (Show Source):
You can put this solution on YOUR website! 12/(9-x)+12/(9+x)=3
(12[9+x]+12[9-x])/(9-x)(9+x)=3
(108+12x+108-12x)/81-x^2=3
3(81-x^2)=216
243-3x^2=216
-3x^2=216-243
-3x^2=-27
x^2=-27/-3
x^2=9
x=sqrt9
x=3 answer for the speed of the stream.
pROOF:
12/(9-3)+12/(9+3)=3
12/6+12/12=3
2+1=3
3=3
(