A project alone takes 45 days and B alone takes 60 days. Now A and B have worked together for a few days, and B leaves for a few days for some reason, and A has been working for 30 days to complete the task. How many days does B leave on the way?
一项工程，甲单独完成需45天，乙单独完成需要60天．现甲、乙合做若干天后，乙因故离开几天，甲一直工作30天完成此项任务．问乙中途离开几天？
<gadget id="calculator">1 / 45</gadget>
<output>1/45 = around 0.022222</output>

<gadget id="calculator">(1/45) * 30</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">1 - (2/3)</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 / 60</gadget>
<output>1/60 = around 0.016667</output>

<gadget id="calculator">(1/3) / (1/60)</gadget>
<output>20</output>

<gadget id="calculator">30 - 20</gadget>
<output>10</output>

<result>10</result>