The length of a rectangular photo frame is 7 decimeters and the width is 2 decimeters. What is the perimeter of this rectangular photo frame?
一个长方形相框的长是7分米，宽是2分米，这个长方形相框的周长是多少分米．
<gadget id="calculator">7 + 2</gadget>
<output>9</output>

<gadget id="calculator">9 * 2</gadget>
<output>18</output>

<result>18</result>