
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
An empty swimming pool was filled with water by two taps, A and B, both with a constant flow rate. For four hours, both taps were open and filled $50\%$ of the pool. Then, tap B was closed and, for two hours, tap A filled $15\%$ of the pool's volume. After this period, tap A was closed and tap B was opened. For how long did tap B need to stay open to finish filling the pool by itself?

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