There are several chickens and rabbits in a cage. Counting from the top, there are 15 heads, and counting from the bottom, there are 46 feet. How many chickens are there?
笼子里有若干只鸡和兔．从上面数，有15个头，从下面数，有46只脚．鸡有多少只．
<gadget id="calculator">2 * 15</gadget>
<output>30</output>

<gadget id="calculator">46 - 30</gadget>
<output>16</output>

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

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

<gadget id="calculator">15 - 8</gadget>
<output>7</output>

<result>7</result>