The worker uncle made bookshelves, and planned to make 17 books a day, and completed the task in 12 days. It actually took 8.5 days to complete the task. How many bookshelves did the worker uncle actually make every day?
工人叔叔做书架，计划每天做17个，12天完成任务，实际用了8.5天就完成了任务，工人叔叔实际平均每天做了多少个书架？
<gadget id="calculator">12 / 8.5</gadget>
<output>1.411765</output>

<gadget id="calculator">17 * 1.411765</gadget>
<output>24.000005</output>

<result>24.000005</result>