The two teachers took 40 students to participate in the aircraft model exhibition. Each ticket is 12.5 yuan, and each group ticket with more than 45 people gets a 20% discount (that is, 8/10 of the original price). How can I buy a ticket?
两位老师带40名同学去参加航模展，每张票12.5元，45人以上的团体票每张打八折(即是原来价钱的十分之八)，计算一下怎样买票合算？
<result>45</result>