There are several chickens and rabbits in the cage. Counting from the top, there are 8 heads and 22 feet. So how many rabbits are there in the cage?
笼子里有鸡兔各若干只，从上面数有8个头，22只脚．那么笼子里有兔多少只．
<gadget id="calculator">2 * 8</gadget>
<output>16</output>

<gadget id="calculator">22 - 16</gadget>
<output>6</output>

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

<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<result>3</result>