Chickens and rabbits have 18 heads and 44 feet. How many chickens are there?
鸡兔共有头18个，脚44只，其中鸡有多少只．
<gadget id="calculator">18 * 4</gadget>
<output>72</output>

<gadget id="calculator">72 - 44</gadget>
<output>28</output>

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

<gadget id="calculator">28 / 2</gadget>
<output>14</output>

<result>14</result>