Two brothers ride bicycles for an outing. The younger brother starts first, at a speed of 200 meters per minute. After 5 minutes, the older brother sets off with a dog, chasing the younger brother at a speed of 250 meters per minute, while the dog runs towards the younger brother at a speed of 300 meters per minute. Go, catch up with the younger brother and return immediately, and immediately chase the younger brother after meeting the older brother, until the older brother catches up with the younger brother, how many kilometers did the dog run at this time?
兄弟两骑车郊游，弟弟先出发，速度每分钟200米，5分钟后，哥哥带一条狗出发，以每分钟250米的速度去追弟弟，而狗则以每分钟300米的速度向弟弟跑去，追上弟弟之后又立即返回，遇到哥哥后又立即向弟弟追去，直到哥哥追上弟弟为止，这时狗跑了多少千米．
<gadget id="calculator">200 * 5</gadget>
<output>1_000</output>

<gadget id="calculator">250 - 200</gadget>
<output>50</output>

<gadget id="calculator">1_000 / 50</gadget>
<output>20</output>

<gadget id="calculator">300 / 1_000</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">20 * (3/10)</gadget>
<output>6</output>

<result>6</result>