A project was originally planned to take 30 days to complete, but it actually took only 20 days. How much work efficiency has been improved.
一项工程原计划需要用30天完成，实际只用了20天，工作效率提高了多少．
<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">1 / 30</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">(1/20) - (1/30)</gadget>
<output>1/60 = around 0.016667</output>

<gadget id="calculator">(1/60) / (1/30)</gadget>
<output>1/2 = around 0.5</output>

<result>1/2 = around 0.5</result>