
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
For a given arithmetic series, the sum of the first $100$ terms is $1800$, and the sum of terms from 51 to 150 is $6300$. What is the first term of the series?
**A)** $-26.55$
**B)** $-20.5$
**C)** $-24.55$
**D)** $-15.55$

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