A project, planned to be completed in 20 days, was actually completed in 16 days, how much the working time was shortened.
一项工程，计划20天完工，实际16天完成，工作时间缩短了多少．
<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>