Question 275490: A boat travels down a river for 4 h (traveling with the current), then turns around and takes 6 h to return (traveling against the current.) Let b be the rate of the boat, in miles per hour, in calm water and c be the rate of the current, in miles per hour. Suppose the distance traveled down the river by the boat is 72 mi. Write a system of equations that can be solved to find the rate of the boat in calm water and the rate of the current.
downstream _______ = 72
upstream ________ = 72
Answer by ankor@dixie-net.com(22740)   (Show Source):
You can put this solution on YOUR website! A boat travels down a river for 4 h (traveling with the current), then turns around and takes 6 h to return (traveling against the current.)
Let b be the rate of the boat, in miles per hour, in calm water and c be the rate of the current, in miles per hour.
Suppose the distance traveled down the river by the boat is 72 mi.
Write a system of equations that can be solved to find the rate of the boat in calm water and the rate of the current.
:
(b - c) = speed upstream
(b + c) = speed down stream
:
Write a dist equation: dist = time * speed
:
4(b + c) = 72
6(b - c) = 72
:
Simplify both equations, divide the 1st by 4, divide the 2nd by 6, results
b + c = 18
b - c = 12
------------------Addition eliminates c, find b
2b = 30
b = 15 mph is the boat speed
:
I'll let you find the current speed (c)
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