If the perimeter of a rectangle is 12 cm and the width is 2 cm, what is the length in cm?
一个长方形的周长是12厘米，宽是2厘米，长应为多少厘米．
<gadget id="calculator">12 / 2</gadget>
<output>6</output>

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

<result>4</result>