Chickens and rabbits are in the same cage with 30 heads and 88 legs. How many chickens are there in the cage?
鸡兔同笼，有30个头，88条腿，笼中鸡有多少只．
<gadget id="calculator">30 * 4</gadget>
<output>120</output>

<gadget id="calculator">120 - 88</gadget>
<output>32</output>

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

<gadget id="calculator">32 / 2</gadget>
<output>16</output>

<result>16</result>