
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
At an oil refinery, a tank was filled with crude oil with a sulfur concentration of $2 \%$. A portion of this oil was then sent for production, and the same amount of oil with a sulfur concentration of $3 \%$ was added to the tank. Again, the same amount of oil was sent for production, but this time oil with a sulfur concentration of $1.5 \%$ was added. As a result, the sulfur concentration in the oil in the tank became the same as it was initially. Determine what fraction of the oil in the tank was sent to production each time.

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