Diana usually drives at an average rate of 30 mph. Today, she is going to drive 12 miles to her friend Tony's house. How many minutes will it take her to get there?

If Diana usually drives at an average rate of 30 mph, then it will take her 12/30 = <<12/30=0.4>>0.4 hours to get to Tony's house.

Since there are 60 minutes in an hour, then it will take her 60 x 0.4 = <<60*0.4=24>>24 minutes to get there. Answer: \boxed{24}.