
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
The distance between places A and B is 420 kilometers. Two cars start from A towards B at the same time. The first car travels at 42 kilometers per hour, and the second car travels at 28 kilometers per hour. After the first car reaches B, it immediately returns. How many hours in total do the two cars use from the start until they meet?

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