
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 total of 270 yuan was paid using only 20 yuan and 50 yuan banknotes by Teacher Zhang. Determine the number of possible ways he could have made the payment.

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