SOLUTION: It took ED 8 hours to row 40km upstream. The return trip, with the aid of the current, took 5 hours. Find the speed of the current. (substitution/elimination)

Question 856398: It took ED 8 hours to row 40km upstream. The return trip, with the aid of the current, took 5 hours. Find the speed of the current. (substitution/elimination)
Answer by lwsshak3(11628) (Show Source): You can put this solution on YOUR website!
It took ED 8 hours to row 40km upstream. The return trip, with the aid of the current, took 5 hours. Find the speed of the current.
**
let c=speed of current
let x=speed of boat in still water
x+c=speed of boat downstream
x-c=speed of boat up stream
travel time=distance/speed
..
40/(x-c)=8
40(x+c)=5
..
8x-8c=40
5x+5c=40
..
40x-40c=200
40x+40c=320
subtract
80c=120
c=120/80=3/2=1.5
speed of current=1.5 km/hr
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