A rectangle with a length of 7 cm and a width of 3 cm. What is its circumference in centimeters?
一个长是7厘米，比宽多3厘米的长方形．它的周长是多少厘米？
<gadget id="calculator">7 - 3</gadget>
<output>4</output>

<gadget id="calculator">7 + 4</gadget>
<output>11</output>

<gadget id="calculator">11 * 2</gadget>
<output>22</output>

<result>22</result>