A factory originally planned to complete a batch of production tasks in 40 days, but actually completed the tasks 10 days ahead of schedule, how much the actual efficiency has improved.
某厂原计划40天完成一批生产任务，实际提前10天完成任务，实际功效提高了多少．
<gadget id="calculator">40 - 10</gadget>
<output>30</output>

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

<gadget id="calculator">1 / 40</gadget>
<output>1/40 = around 0.025</output>

<gadget id="calculator">(1/30) - (1/40)</gadget>
<output>1/120 = around 0.008333</output>

<gadget id="calculator">(1/120) / (1/40)</gadget>
<output>1/3 = around 0.333333</output>

<result>1/3 = around 0.333333</result>