Two brothers start at the same time from the start and end of the 100-meter runway and run in the same direction. The younger brother runs 120 meters per minute in front; the older brother runs 140 meters per minute in the rear. After a few minutes, the elder brother catches up with the younger brother?
兄弟二人从100米跑道的起点和终点同时出发，沿同一方向跑步，弟弟在前，每分钟跑120米；哥哥在后，每分钟跑140米．几分钟后哥哥追上弟弟？
<gadget id="calculator">140 - 120</gadget>
<output>20</output>

<gadget id="calculator">100 / 20</gadget>
<output>5</output>

<result>5</result>