
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 marine biologist is studying the population of trout in a river. On April 1, she captures and tags 80 trout, then releases them back into the river. On August 1, she captures another sample of 100 trout, noticing that 4 of these are tagged. She estimates that 30% of the original tagged trout have left the river system (due to predation or migration), and that 50% of the trout in the August 1 sample were not in the river on April 1 (newly born or migrated into the river). What is the biologist's estimate for the number of trout in the river on April 1?

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