A and B start from the same point on a circular runway with a circumference of 1200 meters and walk in the same direction at the same time. A's speed is 100 m/min, and B's speed is twice that of A's. How many minutes will it take for B to catch up with A for the first time?
甲、乙两人在周长是1200米的环形跑道上从同一地点出发，同时同向而行．甲的速度100米/分，乙的速度是甲的2倍，经过多少分钟，乙第一次能追上甲？
<gadget id="calculator">100 * 2</gadget>
<output>200</output>

<gadget id="calculator">200 - 100</gadget>
<output>100</output>

<gadget id="calculator">1_200 / 100</gadget>
<output>12</output>

<result>12</result>