The bookbinding team ordered a batch of books and planned to bind 840 books. The actual number of books bound every day was 1.5 times that of the planned daily binding. The task was completed in 28 days. How many days were originally planned to complete the task?
装订小组装订一批书，计划装订840册，实际每天装订的册数是计划每天装订的1.5倍，28天完成任务，原计划多少天完成任务？
<gadget id="calculator">840 / 28 / 1.5</gadget>
<output>20</output>

<gadget id="calculator">840 / 20</gadget>
<output>42</output>

<result>42</result>