There are 30 chickens and rabbits with 86 legs, so how many chickens are there?
鸡和兔共30只，有86只脚，那么鸡有多少只．
<gadget id="calculator">4 * 30</gadget>
<output>120</output>

<gadget id="calculator">120 - 86</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>