SOLUTION: a boat traveled 210 miles downstream and back. the trip downstream took 10 hours. the trip back took 70 hours. what is the speed of the boat in still water? what is the speed of

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Question 701190:
a boat traveled 210 miles downstream and back. the trip downstream took 10 hours. the trip back took 70 hours. what is the speed of the boat in still water? what is the speed of the current?
Answer by checkley79(3341) About Me  (Show Source):
You can put this solution on YOUR website!
D=RT
210=R*10 DOWNSTREAM.
R=210/10
R=21 MPH.
210=R*70 UPSTREAM
R=210/70
R=3 MPH. UPSTREAM.
(21+3)/2=24/2=12 MPH. FOR THE BOAT IN STILL WATER.
21-12=9 MPH. FOR THE CURRENT.
PROOF:
3+9=12
21-9=12