Meiyijia Supermarket opens at 9:00 in the morning and closes at 8:00 in the evening. Xiao Min arrives at the supermarket at 8:40 in the morning, how many minutes will she have to wait for the supermarket to open?
美宜佳超市早上9：00开门，晚上8：00关门，小敏早上8：40来到超市，她还要等几分钟超市才开门？
<result>20</result>