SOLUTION: A river has a current of 4mph. Find the speed of Simon's boat in still water if it goes 40 miles downstream in the same time as 24 miles upstream.

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Question 161431: A river has a current of 4mph. Find the speed of Simon's boat in still water if it goes 40 miles downstream in the same time as 24 miles upstream.
Answer by checkley77(12844) About Me  (Show Source):
You can put this solution on YOUR website!
D=RT
40=(X+4)T OR T=40/(X+4)
24=(X-4)T OR T=24/(X-4)
40/(X+4)=24/(X-4) CROSS MULTIPLY.
40(X-4)=24(X+4)
40X-160=24X+96
40X-24X=96+160
16X=256
X=256/16
X=16 MPH IS THE SPEED OF THE BOAT.
PROOF:
40/(16+4)=24/(16-4)
40/20=24/12
2=2