SOLUTION: A boat takes 3 hours to go 42 miles downstream with the current. It takes 4.2 hours to go 42 miles upstream against the current. What is the speed of the current? What is the speed

Algebra ->  Coordinate Systems and Linear Equations -> SOLUTION: A boat takes 3 hours to go 42 miles downstream with the current. It takes 4.2 hours to go 42 miles upstream against the current. What is the speed of the current? What is the speed      Log On


   

Question 590190: A boat takes 3 hours to go 42 miles downstream with the current. It takes 4.2 hours to go 42 miles upstream against the current. What is the speed of the current? What is the speed of the boat?
Answer by lwsshak3(11628) About Me  (Show Source):
You can put this solution on YOUR website!
A boat takes 3 hours to go 42 miles downstream with the current. It takes 4.2 hours to go 42 miles upstream against the current. What is the speed of the current? What is the speed of the boat?
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let x=speed of the boat
let c=speed of the current
net speed with current=x+c
net speed against current=x-c
speed=distance/travel time
..
(x+c)=42/3=14
(x-c)=42/4.2=10
..
x+c=14
x-c=10
add, eliminating c
2x=24
x=12
c=14-x=14-12=2
ans:
speed of the boat=12 mph
speed of the current=2 mph