goes to Shenzhen by car at 9:15, at a speed of 80 kilometers per hour, and walks for 15 minutes; B also goes to Shenzhen by car, and departs at 9:30 at a speed of 100 kilometers per hour. How many minutes does it take B to catch up with A?
甲9：15时坐车去深圳，时速80公里，走了15分钟；乙也坐车去深圳，9：30出发时速100公里．问乙要走多少分钟才能追上甲？
<result>60</result>