What is the perimeter of a rectangle with a length of 6 cm and a width of 4 cm?
长6厘米，宽4厘米的长方形，它的周长是多少厘米．
<gadget id="calculator">6 + 4</gadget>
<output>10</output>

<gadget id="calculator">10 * 2</gadget>
<output>20</output>

<result>20</result>