
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 biologist wants to estimate the number of birds in a forest. On June 1, she captures 80 birds, tags them, and releases them back into the forest. On October 1, she captures another sample of 90 birds, among which 4 are found to be tagged. She assumes that 30% of these birds have left the forest since June (due to migration or death), and that 50% of the birds in the October sample were not in the forest in June (due to new births and migrations). How many birds were in the forest on June 1 according to her calculations?

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