A rectangular garden with a length of 16 meters and a width of 12 meters is surrounded by iron railings. How long is the railing required? If one side is against the wall, how many meters should the iron railing be at least?
一个长方形花园，长16米，宽12米，四周围上铁栏杆，需要栏杆多长？如果一面靠墙，铁栏杆至少要多少米？
<gadget id="calculator">12 * 2</gadget>
<output>24</output>

<gadget id="calculator">16 + 24</gadget>
<output>40</output>

<result>40</result>