There is a circular pool, A. B． The three of them start from a certain point by the pool at the same time and run around the pool. A and B run in the same direction, while C runs in the opposite direction. C meets A on the way, and then meets B after 4 minutes. It is known that A runs 400 meters per minute, B runs 200 meters per minute, and C runs 150 meters per minute. Find the perimeter of this circular pool?
有一个圆形池子，A．B．C三人同时由池边的某一点出发，绕池子跑步．A，B向同一方向跑，C则向相反方向跑．C在途中遇到A，然后经过4分钟又遇到B．已知A每分钟跑400米，B每分钟跑200米，C每分钟跑150米．求这个圆形池子的周长？
<gadget id="calculator">150 + 400</gadget>
<output>550</output>

<gadget id="calculator">200 + 150</gadget>
<output>350</output>

<gadget id="calculator">350 * 4</gadget>
<output>1_400</output>

<gadget id="calculator">400 - 200</gadget>
<output>200</output>

<gadget id="calculator">1_400 / 200</gadget>
<output>7</output>

<gadget id="calculator">550 * 7</gadget>
<output>3_850</output>

<result>3_850</result>