A rectangle is 7 cm long and 5 cm wide, what is its perimeter in cm?
一个长方形长是7厘米，宽是5厘米，它的周长是多少厘米．
<gadget id="calculator">7 + 5</gadget>
<output>12</output>

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

<result>24</result>