The agricultural machinery factory originally planned to manufacture 40 water pumps per day, and the task was completed in 15 days. The actual production was 50 per day, and the actual completion was completed a few days earlier than the original plan?
农机厂原计划每天制造抽水机40台，15天就完成任务，实际每天制造50台，实际比原计划提前几天完成？
<gadget id="calculator">15 / 50</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">40 * (3/10)</gadget>
<output>12</output>

<gadget id="calculator">15 - 12</gadget>
<output>3</output>

<result>3</result>