Uncle Li originally planned to mow a wheat field in 5 hours, but actually it took only 4 hours, which greatly improved the work efficiency.
李大伯原计划5小时割完一块小麦地，实际只用4小时就割完，工作效率提高了多少．
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

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

<gadget id="calculator">(1/4) - (1/5)</gadget>
<output>1/20 = around 0.05</output>

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

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