A piece of work was originally completed in 25 hours, but actually took 20 hours, how much the work efficiency has been improved.
一件工作原25小时完成，而实际用了20小时，则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 / 25</gadget>
<output>1/25 = around 0.04</output>

<gadget id="calculator">(1/20) - (1/25)</gadget>
<output>1/100 = around 0.01</output>

<gadget id="calculator">(1/100) / (1/25)</gadget>
<output>1/4 = around 0.25</output>

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