The bus runs from station A to station B every 5 minutes, and the whole journey takes 15 minutes. A person rides a bicycle from station B to station A. At the beginning, he happens to meet a bus. During the walk, he meets another 10 buses. At station A, another bus is about to leave. How many minutes did this person walk for?
公交车从甲站到乙站每间隔5分钟一趟，全程走15分钟，某人骑自行车从乙站往甲站行走，开始时恰好遇见一辆公交车，行走过程中又遇见10辆，到甲站时又一辆公交车要出发，这人走了多少分钟．
<gadget id="calculator">10 + 1</gadget>
<output>11</output>

<gadget id="calculator">11 * 5</gadget>
<output>55</output>

<gadget id="calculator">55 - 15</gadget>
<output>40</output>

<result>40</result>