A and B start at the same time at point A on the circle and walk towards each other. The speed ratio is 2:3. They meet for the first time at point C, which is 80 meters away from point B. What is the circumference of the circle?
甲，乙两人在圆上A点同时出发，相背而行，速度比是2：3，两人在距B点80米的C点第一次相遇，求圆周长是多少？
<gadget id="calculator">80 / 2</gadget>
<output>40</output>

<gadget id="calculator">2 + 3</gadget>
<output>5</output>

<gadget id="calculator">40 * 5</gadget>
<output>200</output>

<result>200</result>