There are several chickens and rabbits in a cage. Counting from the top, there are 12 heads, and counting from the bottom, there are 32 feet. How many chickens are there in the cage?
笼子里有若干只鸡和兔．从上面数，有12个头，从下面数，有32只脚，笼子里鸡有多少只．
<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>