SOLUTION: A motorboat traveling with the current went 42 mi in 3.5 h. Traveling against the current, the boat went 18 mi in 3 h. Find the rate of the boat in calm water and the rate of the c

Algebra ->  Customizable Word Problem Solvers  -> Travel -> SOLUTION: A motorboat traveling with the current went 42 mi in 3.5 h. Traveling against the current, the boat went 18 mi in 3 h. Find the rate of the boat in calm water and the rate of the c      Log On

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Question 1179660: A motorboat traveling with the current went 42 mi in 3.5 h. Traveling against the current, the boat went 18 mi in 3 h. Find the rate of the boat in calm water and the rate of the current.
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
boat speed= x km/h
current speed= y km/h
with current speed= (x+y)
against current speed (x-y)
d= 42 with current
42 / (x+y) = 3.5
divide by 3.5
12 / (x+y) = 1
(x+y) = 12 ............1
d= = 18 against current
18/(x-y) = 3
divide by 3
6 /(x-y) = 1
x - y = 6 .............2
add up (1) & (2)
2 x = 18
/ 2
x= 9 mph speed of boat in still water
plug value of x in (1)
we get y= 3 mph speed of current