
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
Before the Christmas concert, students offered 60 handmade items for sale, allowing each customer to choose their own price. The entire proceeds were for charity. At the start of the concert, students calculated the average revenue per sold item, which resulted in an exact whole number. Since they had not yet sold all 60 items, they continued to offer them after the concert. Seven more items were bought for a total of 2505 Kč, increasing the average revenue per sold item to exactly 130 Kč. How many items remained unsold?

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