Grandpa Li's house has a rectangular chicken coop against the wall, 7 meters long and 4 meters wide. (the wide side is against the wall), how many meters is the fence required?
李爷爷家有一个靠墙的长方形鸡舍，长7米，宽4米．(宽的一面靠墙)，需栅栏多少米？
<gadget id="calculator">7 * 2</gadget>
<output>14</output>

<gadget id="calculator">14 + 4</gadget>
<output>18</output>

<result>18</result>