A certain project can be completed in 36 days by A alone, and 45 days by B alone. If team A and team B work together at the beginning of the project, and team A quits to start a new project midway, then team B has to work for another 18 days to complete the task. How many days did Team A work?
某项工程，甲单独做需36天完成，乙单独做需45天完成．如果开工时甲，乙两队合做，中途甲队退出转做新的工程，那么乙队又做了18天才完成任务．甲队干了多少天．
<gadget id="calculator">1 / 45</gadget>
<output>1/45 = around 0.022222</output>

<gadget id="calculator">(1/45) * 18</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">1 / 36</gadget>
<output>1/36 = around 0.027778</output>

<gadget id="calculator">(1/36) + (1/45)</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">(3/5) / (1/20)</gadget>
<output>12</output>

<result>12</result>