SOLUTION: This is the question I am having trouble with: In his boat, Carl takes 1 and 1/2 times longer to go 72 miles upstream as it takes for him to make the return trip downstream. If

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Question 188954: This is the question I am having trouble with:
In his boat, Carl takes 1 and 1/2 times longer to go 72 miles upstream as it takes for him to make the return trip downstream. If the boat cruises at 30mph in still water, what is the speed of the current?
Thanks for any help.

Answer by jonvaliente(64) About Me  (Show Source):
You can put this solution on YOUR website!
Let x=speed of the current
30-x = speed of the boat upstream
30+x = speed of the boat downstream
t = time it takes to go downstream
If it takes 1 and 1/2 times longer to go upstream over the same distance, and distance=speed * time
%2830-x%29%2A1.5t=%2830%2Bx%29%2At
45t-1.5xt=30t%2Bxt
15t=2.5xt
Dividing both sides by 2.5t to solve for x, we get:
6=x
The speed of the current is 6mph