A rectangular vegetable field is 13 meters long and 8 meters wide. If the long side is close to the wall and the other three sides are surrounded by fences, how long should the fence be?
一个长方形菜地长13米，宽8米，如果长边靠墙，其他三边用篱笆围起来，篱笆要多少长？
<gadget id="calculator">8 * 2</gadget>
<output>16</output>

<gadget id="calculator">13 + 16</gadget>
<output>29</output>

<result>29</result>