A pillowcase is 7 decimeters long and 4 decimeters wide. If lace is placed around it, how many decimeters of lace is needed at least?
一只枕套长7分米，宽4分米，如果在它的四周镶上花边，至少需要多少分米的花边．
<gadget id="calculator">7 + 4</gadget>
<output>11</output>

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

<result>22</result>