When Xiaohong and Xiaofang are walking on a circular track, they are walking in opposite directions at the same time. Xiaohong walks 50 meters per minute, and Xiaofang walks 40 meters per minute. After the encounter, continue at the original speed and meet again after a total of 6 minutes. What is the circumference of the runway in meters?
小红和小芳在一个圆形跑道上散步时，她们同时在同地向相反方向走，小红每分钟走50米，小芳每分钟走40米．相遇后以原来的速度继续前进，共经过6分钟再次相遇，这个跑道的周长是多少米？
<gadget id="calculator">40 + 50</gadget>
<output>90</output>

<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<gadget id="calculator">90 * 3</gadget>
<output>270</output>

<result>270</result>