A rectangular pillowcase is 5 decimeters long and 3 decimeters wide, with lace sewn around it. How many decimeters of lace is needed to make this headrest cover?
一个长方形枕套长是5分米，宽是3分米，在它四周缝有花边．做这个头枕套，需要花边多少分米？
<gadget id="calculator">5 + 3</gadget>
<output>8</output>

<gadget id="calculator">8 * 2</gadget>
<output>16</output>

<result>16</result>