The distance between Yangyang's home and the school is 5 kilometers, so how many kilometers does it take to go back and forth 4 times a day?
洋洋家离学校的距离是5千米，这样一天来回4趟，需要走多少千米？
<gadget id="calculator">5 * 4</gadget>
<output>20</output>

<result>20</result>