Now there is a 600-meter circular corridor. Four people A, B, C, and D walk 78 meters, 55 meters, 72 meters, and 65 meters per minute respectively. Now A, B, C, and D start at the same point. B walks clockwise, and C and D walk counterclockwise. Then when A and C meet for the first time, how long will it take for B and D to meet for the second time?
现在有一条600米的圆形走廊，A、B、C、D四个人每分钟分别走78米、55米、72米、65米，现在A、B、C、D在同一点出发，A、B按顺时针方向走，C、D按逆时针方向走，那么当A、C第一次相遇后，B、D再过多久第二次相遇？
<gadget id="calculator">65 + 55</gadget>
<output>120</output>

<gadget id="calculator">2 / 120</gadget>
<output>1/60 = around 0.016667</output>

<gadget id="calculator">600 * (1/60)</gadget>
<output>10</output>

<gadget id="calculator">78 + 72</gadget>
<output>150</output>

<gadget id="calculator">600 / 150</gadget>
<output>4</output>

<gadget id="calculator">10 - 4</gadget>
<output>6</output>

<result>6</result>