A rectangular piece of glass is 10 decimeters long and 4 decimeters wide, what is its perimeter?
一块长方形玻璃长是10分米，宽是4分米，它的周长是多少．
<gadget id="calculator">10 + 4</gadget>
<output>14</output>

<gadget id="calculator">14 * 2</gadget>
<output>28</output>

<result>28</result>