It takes 19.8 hours to travel from city A to city B by train. The speed is increased by 20% for the first time, 25% for the second time, and 20% for the third time.
乘火车从甲城到乙城需19.8时，第一次提速20%，第二次提速25%，第三次提速20%，经过这三次提速，从甲城到乙城乘火车需要多少时．
<result>11</result>