There are 30 heads and 94 feet of chickens and rabbits in the same cage. How many rabbits are there?
鸡兔同笼共30个头，94只脚，兔有多少只．
<gadget id="calculator">30 * 4</gadget>
<output>120</output>

<gadget id="calculator">120 - 94</gadget>
<output>26</output>

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

<gadget id="calculator">26 / 2</gadget>
<output>13</output>

<gadget id="calculator">30 - 13</gadget>
<output>17</output>

<result>17</result>