
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
The lengths of the shadows on the days of the twelve solar terms form an arithmetic sequence. The sum of the shadow lengths on the days of the Winter Solstice, the Beginning of Spring, and the Spring Equinox is 31.5 feet, and the sum of the shadow lengths on the days of the first nine solar terms is 85.5 feet. Find the shadow length on the day of the Grain in Ear.

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