
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 the slope of line $l_1$ is $3$, and line $l_2$ passes through points $A(1,2)$ and $B(2, a)$. If line $l_1$ is parallel to line $l_2$, find the value of $a$; if line $l_1$ is perpendicular to line $l_2$, find the value of $a$.

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