I know this is a really easy question, but it's Friday and I hardly got any sleep last night and I really can't think anymore.

I work in a Call Centre and what I want to do is work out the average number of calls someone takes per hour.

I have the number of calls they took in the day, as well as the number of hours and minutes they spent on the phones.

Obviously it's just a case of dividing one by the other, however given that one is a number and the other is time, i'm having problems figuring out how to do this.

Any idea?