There are several chickens and rabbits in the cage. There are 12 heads and 32 legs. How many chickens are there?
笼子里有鸡兔若干只，一共有头12个，腿32条，鸡有多少只．
<gadget id="calculator">12 * 2</gadget>
<output>24</output>

<gadget id="calculator">32 - 24</gadget>
<output>8</output>

<gadget id="calculator">4 - 2</gadget>
<output>2</output>

<gadget id="calculator">8 / 2</gadget>
<output>4</output>

<gadget id="calculator">12 - 4</gadget>
<output>8</output>

<result>8</result>