A rectangle with a length of 5 cm and a width of 4 cm is surrounded by a wire. What is the length of the wire in cm?
用一根铁丝围成一个长5厘米、宽4厘米的长方形，这根铁丝长多少厘米．
<gadget id="calculator">5 + 4</gadget>
<output>9</output>

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

<result>18</result>