If the length of a rectangle is 7 meters and the width is 3 meters, what is the circumference in decimeters?
一个长方形的长是7米，宽是3米，周长是多少分米．
<gadget id="calculator">7 + 3</gadget>
<output>10</output>

<gadget id="calculator">10 * 2 * 10</gadget>
<output>200</output>

<result>200</result>