
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 that the slope angle of line l is $\frac{3}{4}\pi$, line $l_1$ passes through points A(3, 2) and B(a, -1), and $l_1$ is perpendicular to $l$, line $l_2$: $2x+by+1=0$ is parallel to line $l_1$, calculate the value of $a+b$.

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