Five students surnamed Zhao, Qian, Sun, Li and Zhou, one year older than the other, a total of 60 years old, now know that Zhao is older than Li; Sun is older than Qian, younger than Zhou; Qian is older than Li; Zhou is younger than Zhao; So how old is Sun?
赵、钱、孙、李和周姓五个同学，他们一个比一个大一岁，合计60岁，现知赵比李大；孙比钱大，比周小；钱比李大；周比赵小；那么孙是多少岁．
<gadget id="calculator">60 - 1 - 2 - 3 - 4</gadget>
<output>50</output>

<gadget id="calculator">50 / 5</gadget>
<output>10</output>

<gadget id="calculator">10 + 2</gadget>
<output>12</output>

<result>12</result>