A 12-meter-long iron wire is used to form a rectangle, the length of the rectangle is 4 meters, and the width is how many meters.
用一根12米长的铁丝围成一个长方形，长方形的长是4米，宽是多少米．
<gadget id="calculator">12 / 2</gadget>
<output>6</output>

<gadget id="calculator">6 - 4</gadget>
<output>2</output>

<result>2</result>