The ticket price of an exposition has been reduced by 20% compared with the last time, and the number of visitors has increased by half compared with the last time. Therefore, the revenue has increased by what percentage compared with the last time?
某博览会门票价格比上次降低了20%，而观众人数比上次增加了一半，因此收入比上一次增加了百分之几？
<result>0.6</result>