
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
If student A and B set off from two locations 800 meters and 400 meters away from the activity location, and student A's speed is 1.2 times that of student B's speed, such that student B arrives at the activity location 4 minutes ahead of student A, the correct equation is 

$\frac{x}{800}-\frac{1.2x}{400}=4$

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