rectangular vegetable field is 15 meters long and 7 meters wide. Now it needs to be surrounded by a fence, and one side is against the wall. How much fence is needed at least?
一块长方形菜地，长15米，宽7米，现在要围上篱笆，一面靠墙，至少要多少篱笆？
<gadget id="calculator">7 * 2</gadget>
<output>14</output>

<gadget id="calculator">15 + 14</gadget>
<output>29</output>

<result>29</result>