SOLUTION: A boy swims downstream 0.9 miles in the same amount of time that he can swim 0.6 miles upstream. If the rate of the current is 1.5 mph, how fast can he swim in still water?

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Question 205999: A boy swims downstream 0.9 miles in the same amount of time that he can swim 0.6 miles upstream. If the rate of the current is 1.5 mph, how fast can he swim in still water?
Answer by checkley77(12844) About Me  (Show Source):
You can put this solution on YOUR website!
D=RT OR T=D/R
T=.9/(R+1.5)
T=.6/(R-1.5)
.9/(R+1.5)=.6/(R-1.5)
.6(R+1.5)=.9(R-1.5)
.6R+.9=.9R-1.35
.6R-.9R=-1.35-.9
-.3R=-2.25
R=-22.5/-.3
R=7.5 MPH IS HIS QWIMMING SPEED IN STILL WATER.
PROOF:
.9/(7.5+1.5)=.6/(7.5-1.5)
.9/9=.6/6
.1=.1