It took Xiao Ming 30 hours to write a manuscript alone, and Xiao Hua needed 20 hours. After they worked together for a few days, Xiaohua fell ill and couldn’t continue to work. It took 18 hours to type this manuscript. How many hours did Xiaohua stop due to illness? ?
独打一篇文稿，小明需要30小时，小华需要20小时，在他们合做一些天后，小华生病未能继续工作，打这篇文稿一共用了18小时，求小华生病停了多少小时？
<gadget id="calculator">1 / 30</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">(1/30) * 18</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">1 - (3/5)</gadget>
<output>2/5 = around 0.4</output>

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

<gadget id="calculator">(2/5) / (1/20)</gadget>
<output>8</output>

<gadget id="calculator">18 - 8</gadget>
<output>10</output>

<result>10</result>