A, B, and C are on the same highway. A is at a T-junction between B and C. C is on the west and B is on the east. The distance between B and C is 700 meters. B and C are walking towards each other at the same time. Walk 60 meters per minute. After 5 minutes, the two meet. At this time, B is 80 meters beyond the T-junction. When B and C meet, A immediately goes south, and B immediately returns and goes south through the T-junction. C travels 10 meters less than A per minute. How many minutes can B catch up with A after A starts?
甲、乙、丙三人在同一条公路上，甲在乙丙之间的丁字路口上，丙在西，乙在东，乙丙之间相距700米，乙丙二人同时相向而行，丙每分钟走60米，经过5分钟两人相遇，这时乙超过丁字路口80米，当乙丙相遇时，甲立即向南而行，乙立即返回并经过丁字口向南而行．丙每分钟比甲少行10米，问甲出发后几分钟乙可以追上甲？
<result>8</result>