The perimeter of the rectangle is 12 meters, the known width is 2 meters, how many meters is the length?
长方形的周长是12米，已知宽是2米，长是几米？
<gadget id="calculator">12 / 2</gadget>
<output>6</output>

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

<result>4</result>