The speed of car A is 60 km/h, and the speed of car B is 36 km/h. Car A and car B start from A and B at the same time respectively, and meet each other after 2 hours and 40 minutes. If cars A and B want to meet at the midpoint of places A and B, then how many minutes before car B will start from B.
甲车速度为60千米/时，乙车速度为36千米/时，甲、乙两车分别从A、B两地同时出发，过2小时40分钟后相遇．如果甲、乙两车要在A、B两地的中点相遇，那么乙车要比甲车提前多少分钟从B地出发．
<gadget id="calculator">123 - 73.6</gadget>
<output>49.4</output>

<gadget id="calculator">49.4 / 36</gadget>
<output>1.372222</output>

<result>1.372222</result>