Question 376030
let speed of current be x kph
speed in still water = 15 kph
..
speed upstream = 15-x
speed downstream = 15+x
..
distance upstream = 35 km
distance downstream = 140 km.
..
time upstream = time downstream
..
t = d/r
35/(15-x) = 140/( 15+x)
cross multiply
35(15+x) =140(15-x)
525+35x=2100-140x
35x+140x=2100-525
175x=1575
/175
x= 1575/175
x = 9kmh ... speed of current
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