A rectangle has a width of 4 cm and a perimeter of 26 cm, what is its length in cm?
一个长方形的宽是4厘米，周长是26厘米，它的长是多少厘米．
<gadget id="calculator">26 / 2</gadget>
<output>13</output>

<gadget id="calculator">13 - 4</gadget>
<output>9</output>

<result>9</result>