
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
To strengthen the water conservation awareness of citizens, a certain city has established the following water usage fee standards: when the monthly water usage of each household does not exceed $6$ tons, the water price is $2$ yuan per ton; when it exceeds $6$ tons, the excess part is charged at $3$ yuan per ton. In a certain household in the city, the water usage in May is $x$ tons, and the water fee to be paid is $y$ yuan.
$(1)$ Find the functional expression of $y$ in terms of $x$;
$(2)$ If the water fee for this household in May is $27$ yuan, what is the water usage in tons for that month?

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