To make a batch of bookcases, it is planned to make 17 a day, and it will be completed in 20 days; the task is actually completed in 8.5 days. How many bookcases are actually made on average per day?
做一批书柜，计划每天做17个，20天完成；实际8.5天就完成了任务，实际平均每天做多少个书柜？
<gadget id="calculator">20 / 8.5</gadget>
<output>2.352941</output>

<gadget id="calculator">17 * 2.352941</gadget>
<output>39.999997</output>

<result>39.999997</result>