A rectangle is 4 meters wide and 50 decimeters long, what is its perimeter in meters?
一个长方形宽4米，长50分米，它的周长是多少米．
<gadget id="calculator">50 / 10</gadget>
<output>5</output>

<gadget id="calculator">5 + 4</gadget>
<output>9</output>

<gadget id="calculator">9 * 2</gadget>
<output>18</output>

<result>18</result>