Today there are chickens and rabbits in the same cage, with 40 heads on the top and 96 feet on the bottom. Then how many rabbits are there?
今有鸡兔同笼，上有40头，下有96足．则兔有多少只．
<gadget id="calculator">40 * 2</gadget>
<output>80</output>

<gadget id="calculator">96 - 80</gadget>
<output>16</output>

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

<gadget id="calculator">16 / 2</gadget>
<output>8</output>

<result>8</result>