A project was originally planned to be completed in 20 days, but it was actually completed in 15 days. How much has the working time been shortened?
一项工程原计划20天完成，实际15天完成，工作时间缩短了多少．
<gadget id="calculator">20 - 15</gadget>
<output>5</output>

<gadget id="calculator">5 / 20</gadget>
<output>1/4 = around 0.25</output>

<result>1/4 = around 0.25</result>