Together, two wildlife refuge tour guides each lead twelve 45-minute tours each day. The wildlife refuge needs to calculate the person-hours for the tours to allocate enough money in their budget to pay the tour guides. What is the number of person-hours per day for the tours?
Each tour guide leads 12 tours per day, so together they lead 24 tours per day (12+12=24).
Each tour lasts 45 minutes, so 24 tours will last for 24*45 = <<24*45=1080>>1080 minutes per day.
One hour is 60 minutes, so 1080 minutes equals 1080/60 = <<1080/60=18>>18 person-hours per day for the tours. Answer: \boxed{18}.