Put some chickens and rabbits in a cage. There are 29 heads from the top and 92 feet from the bottom. How many chickens are there in the cage?
把一些鸡和兔子放在一只笼子里，从上面数有29个头，从下面数有92只脚，那么笼子中有鸡多少只．
<gadget id="calculator">29 * 2</gadget>
<output>58</output>

<gadget id="calculator">92 - 58</gadget>
<output>34</output>

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

<gadget id="calculator">34 / 2</gadget>
<output>17</output>

<gadget id="calculator">29 - 17</gadget>
<output>12</output>

<result>12</result>