To complete a task, Master Li needs 20 hours to do it alone, and Master Wang needs 30 hours to do it alone. Now he is working together, and Master Li asks for 5 hours of leave in the middle. How many hours will it take to complete the task?
完成一项任务，李师傅独做需20小时，王师傅独做需30小时，现在合作工作，李师傅中途请假5小时，完成任务一共用多少小时？
<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</output>

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

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

<gadget id="calculator">(1/30) * 5</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">1 - (1/6)</gadget>
<output>5/6 = around 0.833333</output>

<gadget id="calculator">(1/4) + (1/6) + (5/6)</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">(1/20) + (1/30)</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">(5/4) / (1/12)</gadget>
<output>15</output>

<result>15</result>