SOLUTION: Find the speed of a motor boat in still water and the speed of a river current, if it takes 3 hrs. to travel a distance of 45m. upstream and 2 hrs. to travel 50 m. downstream.

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: Find the speed of a motor boat in still water and the speed of a river current, if it takes 3 hrs. to travel a distance of 45m. upstream and 2 hrs. to travel 50 m. downstream.       Log On


   

Question 48227: Find the speed of a motor boat in still water and the speed of a river current, if it takes 3 hrs. to travel a distance of 45m. upstream and 2 hrs. to travel 50 m. downstream.
Answer by Paul(988) About Me  (Show Source):
You can put this solution on YOUR website!
Let x be the boat's speed and let y be the speed of the current
EQUATION 1:
upstream = -
-->3x-3y=45
EQUATION 2:
Downstream = +
-->2x+2y=50
Multiply E1 by 2 and E2 by 3
6x-6y=90
6x+6y=150
add:
12x=240
x=20
3(20)-3y=45
-3y=-15
y=5
Hence, the speed of the boat is 20mph and the speed of the current is 5mph.
Paul.