
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 high-speed train and a regular train have lengths of 400 meters and 600 meters, respectively. They are moving towards each other at constant speeds on parallel tracks. If a passenger on the high-speed train observes the regular train passing by the window in 3 seconds, determine the time it takes for a passenger on the regular train to see the high-speed train pass by the window.

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