
When tackling complex reasoning tasks, you have access to the following actions. Use them as needed to progress through your thought process.

[ASSESS]

[ADVANCE]

[VERIFY]

[SIMPLIFY]

[SYNTHESIZE]

[PIVOT]

[OUTPUT]

You should strictly follow the format below:

[ACTION NAME]

# Your action step 1

# Your action step 2

# Your action step 3

...

Next action: [NEXT ACTION NAME]


system
A person rows a boat for 15 li. If he rows at his usual speed, the time taken to row downstream is 5 hours less than rowing upstream. If he rows at twice his usual speed, the time taken to row downstream is only 1 hour less than rowing upstream. What is the speed of the water flow in li/hour?

Present the answer in LaTex format: \boxed{Your answer}
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