It took Uncle Zhang and Aunt Li 5 days to dig half of a canal. If Uncle Zhang digs alone, it will take 15 days to finish digging. According to this calculation, if Aunt Li digs alone, how long will it take to finish digging?
一条水渠，张叔叔和李阿姨用了5天时间才刚好挖了一半．如果张叔叔单独挖要15天才能挖完，照这样计算，如果李阿姨单独挖，那要多少时间挖完呢？
<gadget id="calculator">5 * 2</gadget>
<output>10</output>

<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">(1/10) - (1/15)</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">1 / (1/30)</gadget>
<output>30</output>

<result>30</result>