There are 20 chickens and rabbits, with a total of 46 legs. How many chickens are there?
有鸡和兔20只，共有46只脚，鸡有多少只．
<gadget id="calculator">20 * 4</gadget>
<output>80</output>

<gadget id="calculator">80 - 46</gadget>
<output>34</output>

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

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

<result>17</result>