
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
Suppose the regression line equation for a worker's monthly salary $(y$, in yuan) based on changes in labor productivity $(x$, in 10,000 yuan) is given by $\hat{y} = 60 + 90x$. Among the following statements, the correct one is ___.
(Fill in the blank with the corresponding number)
$①$ When labor productivity is 10,000 yuan, the salary is 50 yuan.
$②$ When labor productivity increases by 10,000 yuan, the salary increases by 150 yuan.
$③$ When labor productivity increases by 10,000 yuan, the salary increases by 90 yuan.
$④$ When labor productivity is 10,000 yuan, the salary is 90 yuan.

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