If the length of a rectangle is 7 meters and the width is 50 decimeters, what is its perimeter?
一个长方形的长是7米，宽是50分米，它的周长是多少．
<gadget id="calculator">50 / 10</gadget>
<output>5</output>

<gadget id="calculator">7 + 5</gadget>
<output>12</output>

<gadget id="calculator">12 * 2</gadget>
<output>24</output>

<result>24</result>