
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 the altitude increases by $100$ meters, the temperature decreases by $0.3^{\circ}\mathrm{C}$. It is known that the altitude at the foot of a certain mountain is $1230$ meters and the temperature is $18^{\circ}\mathrm{C}$, while the temperature at the mountaintop is $16.2^{\circ}\mathrm{C}$. Find the altitude of the mountaintop.

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