It took Xiao Ming 16 minutes to complete the planned 20 minutes of work, and the working time he used was less than the plan ((())/(())).
小明用了16分钟完成了计划20分钟的工作，他所用工作时间比计划少用了((())/(()))．
<gadget id="calculator">20 - 16</gadget>
<output>4</output>

<gadget id="calculator">4 / 20</gadget>
<output>1/5 = around 0.2</output>

<result>1/5 = around 0.2</result>