9 adventurers lost their way in the desert. When they woke up in the morning, they found that the drinking water they brought was only enough for 5 days. At this time, they found some footprints and knew that some people were also in the desert, so they tracked them down. After catching up that night, they found that those people had no water to drink. From the next day, the two groups of people shared the remaining water, which was only enough to drink for 3 days. Do you know how many people there are in the second group?
9个冒险者在沙漠中迷了路．早晨起来一看，所带的饮用水只够喝5天了，此时，他们发现了一些足印，知道还有一些人也在沙漠中，于是寻踪追去．当天晚上追上以后，发现那些人已经没有水喝了，从次日起，两批人合用剩下的水，只够喝3天．你知道第二批人共有多少个．
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 / 5 / 9</gadget>
<output>1/45 = around 0.022222</output>

<gadget id="calculator">(4/5) / 3 / (1/45)</gadget>
<output>12</output>

<gadget id="calculator">12 - 9</gadget>
<output>3</output>

<result>3</result>