
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
A  $9 \times 9$  square consists of  $81$  unit squares. Some of these unit squares are painted black, and the others are painted white, such that each  $2 \times 3$  rectangle and each  $3 \times 2$  rectangle contain exactly 2 black unit squares and 4 white unit squares. Determine the number of black unit squares.

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