A job needs 30 hours to be completed by A alone, 20 hours to be completed by B alone, and 40 hours to be completed by C alone. Now after 3 hours of cooperation between A and B on this job, A leaves due to something, and after another 3 hours, C Joined until the work was completed, how many hours did it take to complete the work?
一件工作，甲单独完成需要30小时，乙单独完成，需要20小时，丙单独完成，需要40小时，现在这件工作甲乙合作3小时后，甲因有事离开了，又过3小时后，丙加入进来，直到工作完成，完成这件工作共用了多少小时？
<gadget id="calculator">1 / 30</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</output>

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

<gadget id="calculator">(1/12) * 3</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/20) * 3</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">1 - (1/4) - (3/20)</gadget>
<output>3/5 = around 0.6</output>

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

<gadget id="calculator">(1/20) + (1/40)</gadget>
<output>3/40 = around 0.075</output>

<gadget id="calculator">(3/5) / (3/40)</gadget>
<output>8</output>

<gadget id="calculator">8 + 3 + 3</gadget>
<output>14</output>

<result>14</result>