A piece of rectangular glass is 15 decimeters long and 9 decimeters wide. A frame is to be placed on it. What is the length of the frame?
一块长方形玻璃，长15分米，宽9分米，要给它镶个框，框的长度是多少分米？
<gadget id="calculator">15 + 9</gadget>
<output>24</output>

<gadget id="calculator">24 * 2</gadget>
<output>48</output>

<result>48</result>