It takes Li Qiang 9 minutes to walk from home to school, and he goes home for lunch. How long does it take Li Qiang to go to and from home and school every day?
李强从家步行到学校要9分钟，中午回家吃饭．李强每天往返家与学校一共要走多长时间？
<gadget id="calculator">9 * 4</gadget>
<output>36</output>

<result>36</result>