Annalise works out with a treadmill program that varies the amount of time she runs and walks. She has the treadmill set to a walking speed of 15 minutes per mile and a running speed of 9 minutes per mile. The amount of time running and walking can be different for every workout, but she always does a total of 6 miles. Write three other combinations of running and walking times that Annalise could spend on the treadmill.