There are 10 chickens and rabbits and 22 legs. How many rabbits are there?
鸡与兔共10只，脚共22只，问兔有多少只．
<gadget id="calculator">2 * 10</gadget>
<output>20</output>

<gadget id="calculator">22 - 20</gadget>
<output>2</output>

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

<gadget id="calculator">2 / 2</gadget>
<output>1</output>

<result>1</result>