A rectangle is 8 cm long and 7 cm wide, what is its perimeter in cm
一个长方形长是8厘米，宽是7厘米，它的周长是多少厘米
<gadget id="calculator">8 + 7</gadget>
<output>15</output>

<gadget id="calculator">15 * 2</gadget>
<output>30</output>

<result>30</result>