rectangular nursery is 84 meters long and 56 meters wide. A fence around the nursery, how many meters long is the fence?
一个长方形苗圃，长84米，宽56米．在苗圃四周围一圈篱笆，篱笆长多少米？
<gadget id="calculator">84 + 56</gadget>
<output>140</output>

<gadget id="calculator">140 * 2</gadget>
<output>280</output>

<result>280</result>