
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
Given that a school has 21 elementary teachers, 14 intermediate teachers, and 7 senior teachers, if a random sample of 6 teachers is selected using stratified random sampling, and two additional teachers are randomly selected for further data analysis, determine the probability that both selected teachers are elementary teachers.

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