
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 car with mail departed from $A$ to $B$. Twenty minutes later, a second car left on the same route at a speed of 45 km/h. After catching up with the first car, the driver of the second car handed over a package and immediately returned to $A$ at the same speed (time spent for stop and turnaround is not considered). By the time the first car arrived at $B$, the second car had only reached halfway from the meeting point back to $A$. Find the speed of the first car, given that the distance between $A$ and $B$ is 40 km.

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