The long-distance bus arrived earlier than usual today. The bus station immediately sent someone to ride a bicycle to deliver the mail accompanying the shuttle to the post office. After walking for half an hour, the bicycle encountered a motorcycle sent by the post office to pick up the mail. After the rider took the mail, he turned around and returned to the post office without any delay. Arrived 20 minutes early. If the departure time and speed of the motorcycle to pick up the mail at the station are the same every day, how many minutes earlier will the long-distance bus arrive at the station today?
今天长途班车比往常早到站了．汽车站立即派人骑自行车将随班车的邮件送往邮局，自行车走了半小时，遇到邮局派出取邮件的摩托车，车手接过邮件后，一点也不耽搁掉头就返回邮局，结果比往常早到了20分钟．如果摩托车每天去车站取邮件的出发时间和行驶速度都一样，那么今天长途班车比往常到站时间提前了几分钟？
<gadget id="calculator">20 / 2</gadget>
<output>10</output>

<gadget id="calculator">30 + 10</gadget>
<output>40</output>

<result>40</result>