SOLUTION: A boat travels 60 miles upstream in 5 hours. The boat travels the same distance downstream in 3 hours. Find the rate of the boat still water and rate of the current?

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Question 584673: A boat travels 60 miles upstream in 5 hours. The boat travels the same distance downstream in 3 hours. Find the rate of the boat still water and rate of the current?
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
Boat speed =x mph
current speed =y mph
against wind x-y 5 hours
with wind x+y 3 hours

Distance = same= upstream= 60 miles Downstream = 60 miles
t=d/r against current
60 / ( x - y )= 5
5 ( x - y ) = 60
5 x - 5 y = 60 ....................1

60 / ( x + y )= 3
3 ( x + y ) = 60
3 x + 3 y = 60 ...............2
Multiply (1) by 3
Multiply (2) by 5
we get
15 x + -15 y = 180
15 x + 15 y = 300
30 x = 480
/ 30
x = 16 mph

plug value of x in (1)
5 x -5 y = 60
80 -5 y = 60
-5 y = 60 -80
-5 y = -20
y = 4 mph
Boat 16 mph
current 4 mph