SOLUTION: a boat travels 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 t

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: a boat travels 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 t      Log On


   

Question 250290:
a boat travels 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 checkley77(12844) About Me  (Show Source):
You can put this solution on YOUR website!
D=RT
210=R*10
210=10R
R=210/10
ER-21 MPH. FOR THE TRIP DOWNSTREAM.
210=R*70
R=210/70
R=3 MPH FOR THE TRIP UPSTREAM.
(10-3)/2=7/2=3.5 MPH IS THE CURRENT SPEED.
10-3.5=6.5 MPH FOR THE BOAT.
3+3.5=6.5 DITTO.