
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
Given vectors $\overrightarrow{a}=\overrightarrow{{e_1}}+\overrightarrow{{e_2}}$ and $\overrightarrow{b}=\overrightarrow{{e_1}}-3\overrightarrow{{e_2}}$, where $\overrightarrow{{e_1}}$ and $\overrightarrow{{e_2}}$ are unit vectors, and the angle between vectors $\overrightarrow{{e_1}}$ and $\overrightarrow{{e_2}}$ is $120^{\circ}$, find $\overrightarrow{a}•\overrightarrow{b}=$____.

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