SOLUTION: A motorboat travels 147 in 3 hours going upstream. It travels 231 going downstream in the same amount of time. What is the rate of the boat in still water and what is the rate of t

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Question 860331: A motorboat travels 147 in 3 hours going upstream. It travels 231 going downstream in the same amount of time. What is the rate of the boat in still water and what is the rate of the current?
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
motor boat speed =x mph
current speed =y mph
against current 3 hours
with current 3 hours

Distance with current 231 miles distance against current 147
t=d/r against current (x-y)
147.00 / ( x - y )= 3.00

3.00 x - -3.00 y = 147.00 ....................1
with current (x+y)
231.00 / ( x + y )= 3.00
3.00 ( x + y ) = 231.00
3.00 x + 3.00 y = 231.00 ...............2
Multiply (1) by 1.00
Multiply (2) by 1.00
we get 2.00
3.00 x + -3.00 y = 147.00
3.00 x + 3.00 y = 231.00
6.00 x = 378.00
/ 6.00
x = 63 mph

plug value of x in (1) y
3 x -3 y = 147
189 -3 -189 = 147
-3 y = 147
-3 y = -42 mph
y = 14
motor boat 63 mph
current 14 mph