First find how fast each runs. Apple = 24 miles / 3 miles per hour = <<24/3=8>>8 hours
Mac = 24 miles / 4 miles per hour = <<24/4=6>>6 hours.
Mac runs 8 hours - 6 hours = <<8-6=2>>2 hours faster.
1 hour = 60 minutes, so, Mac runs faster by 2 hours * 60 minutes = <<2*60=120>>120 minutes.
#### 120