In the country of plants, Ritsuko found a wave of Haruka, and Miss Ritsu wanted to catch them back, but Haruka and the local plants became good friends, and the plants were being attacked by the neighboring country - the country of zombies. Therefore, Xiao Chunxiang decided to help the plant friends repel the invasion of the zombie country before returning to the office. It is known that the kingdom of zombies is continuously sending zombies to attack the kingdom of plants. If 30 little spring fragrances help, then the invading army of the zombie kingdom can be repelled in 9 hours; if 40 little spring fragrances help, then 6 hours can fight Repel the invading army of the zombie country. Now there are 50 Xiao Chunxiang present, and they decided to help all of them, so that they can repel the invading army of the Zombie Kingdom in a few hours.
在植物之国，律子小姐找到了一波小春香，律子小姐要抓小春香们回去，但是小春香们和当地的植物结成了好朋友，而植物们正遭到邻国--僵尸之国的侵略，于是小春香们决定帮助植物朋友们打退僵尸之国的侵略再回事务所．已知，僵尸之国正源源不断地派遣僵尸进攻植物之国，如果有30只小春香帮忙，那么9小时可以打退僵尸之国的侵略军；如果有40只小春香帮忙，那么6小时可以打退僵尸之国的侵略军．现在在场的小春香一共有50只，她们决定全部都去帮忙，那么多少小时就可以打退僵尸之国的侵略军．
<gadget id="calculator">40 * 6</gadget>
<output>240</output>

<gadget id="calculator">30 * 9</gadget>
<output>270</output>

<gadget id="calculator">270 - 240</gadget>
<output>30</output>

<gadget id="calculator">9 - 6</gadget>
<output>3</output>

<gadget id="calculator">30 / 3</gadget>
<output>10</output>

<gadget id="calculator">10 * 6</gadget>
<output>60</output>

<gadget id="calculator">240 - 60</gadget>
<output>180</output>

<gadget id="calculator">50 - 10</gadget>
<output>40</output>

<gadget id="calculator">180 / 40</gadget>
<output>9/2 = around 4.5</output>

<result>9/2 = around 4.5</result>