person M flies from point A to point B by plane on time every morning. When he arrives at the airport of point B, a special car will arrive on time and take M to point C. One day, the plane arrived an hour earlier. After getting off the plane, M walked towards point C on foot. He encountered a special car on the way and arrived at point C by car. The result was that he arrived 20 minutes earlier than usual. Q: How long has M been on the road? how many minutes
一个人M每天早晨准时坐飞机从A地飞到B地，一到B地机场，准时会有一辆专车到达，把M送到C地．某天飞机早到一个小时，M下飞机后徒步向C地走，半路遇到专车后乘车到达C地，结果比平时早到20分钟．问：M在路上走了多长时间？多少分钟
<gadget id="calculator">20 / 2</gadget>
<output>10</output>

<gadget id="calculator">60 - 10</gadget>
<output>50</output>

<result>50</result>