Question 788146
The total trip takes 8 hours

rate downstream =  b+c where b is boat speed and c is current speed

rate upstream = b-c

downstream
36/(b+c)+36/(b-c)=8

substitute 1/(b+c) =x
1/(b-c)=y
36x+36y=8

Upstream is 60 km

60/(b-c)=10

let 1/(b-c)=y

60y=10
y=1/6

substitute y in 36x+36y=8
36x+36/6 =8
36x=2
x=1/18
1/(b-c)=1/18
.
b+c=18
b-c=6
add the equations

2b=24
b=12km/h speed of boat
plug b to get c speed of current

m.ananth@hotmail.ca



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