SOLUTION: A boat traveled 210 miles downstream and back. The trip downstream too 10 hours. The trip back took 70 hours. What is the speed of the boat in still water? What is the speed of

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: A boat traveled 210 miles downstream and back. The trip downstream too 10 hours. The trip back took 70 hours. What is the speed of the boat in still water? What is the speed of      Log On


   

Question 183098: A boat traveled 210 miles downstream and back. The trip downstream too 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!
210/10=21 mph is the speed downstream
210/70=3 mph is the speed upstream.
(21+3)/2=24/2=12 mph is the current speed.
Proof:
21-12=9 mph is the boat speed in still water.
12-9=3 mph ditto.