SOLUTION: I know this is a d = r x t problem, but am a bit confused as to how to get the answer. A tugboat pushing a barge up the Ohio River takes 1 hour longer to travel 36 miles up the

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Question 34621This question is from textbook Merrill Algebra 1 Applications and Connections
: I know this is a d = r x t problem, but am a bit confused as to how to get the answer.
A tugboat pushing a barge up the Ohio River takes 1 hour longer to travel 36 miles up the river than to travel the ame distance down the river. If the rate of the current is 3 mph, find the speed of the tugboat and barge in still water.
I figured the rate of the boat going upstream is r - 3 and going downstream is r + 3. The part that threw me is the "one hour longer" part..please help!
This question is from textbook Merrill Algebra 1 Applications and Connections

Answer by Paul(988) About Me  (Show Source):
You can put this solution on YOUR website!
One hour longer means that "one hour added to the distance going upstream/downstream"
Equation: Letting x be the current
36%2F%28x%2B3%29%2B1=36%2F%28x-3%29
36%2F%28x-3%29-36%2F%28x%2B3%29=1
Cross mutiply:
36[(x+3)-(x-3)]=(x-3)(x+3)
36%286%29=x%5E2-9
x%5E2=225
x=15
Hence, the speed of the tugboat and barge is 15mph in still water.
Paul.