job started on June 1st and was originally scheduled to be completed in one month, but the actual work was completed on June 20th. According to this calculation, how much will be overfulfilled by June 30.
一项工作，6月1日开工，原定一个月完成，实际工作到6月20日就完成了任务．照这样计算，到6月30日将超额完成多少．
<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">(1/20) * 30</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">(3/2) - 1</gadget>
<output>1/2 = around 0.5</output>

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

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