How many of them?

Remember A & B? They seem enjoy the guessing. So, they have another communication again to thier bran exercise.
A: Hi, boss. Remember me? I'm the one asking about your childrens age last week.
B: Sure I remember you, you're a smart guy.
A: So, another question today, I would like to know how many customer coming to your shop daily?
B: Haha~~you guess?
A: Any hint?
B: Well, 1/2 of them are office lady, 1/4 is foreigner, 1/7 is government staff, 1/12 is my old friends, and 4 of them is student.
A: I already get the answer......

So, how many customer daily come to this shop?