A and B are running on a 400-meter circular track. They run in opposite directions. The first meeting and the second meeting are separated by 40 seconds. It is known that A runs 6 meters per second and how many meters B runs per second.
甲乙两人在400米的环形跑道上跑步，两人朝相反的方向跑，第一次相遇和第二次相遇相隔40秒，已知甲每秒跑6米，乙每秒跑多少米．
<gadget id="calculator">400 / 40</gadget>
<output>10</output>

<gadget id="calculator">10 - 6</gadget>
<output>4</output>

<result>4</result>