
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
Three sisters are standing in line for the ski lift at a ski slope with their instructor. Out of boredom, the instructor asked the oldest sister how old they are.

"I will only say," she replied, "that if you subtract nine times the age of my youngest sister from the product of my age and my middle sister's age, you will get 89."

The instructor remembered that the middle sister had just gotten new skis, and that her parents had given them to her for her tenth birthday. Then he easily determined the age of each sister.

Can you do the same?

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