Two ice cream machines make a total of 320 gallons in a certain amount of time. Working together for the same length of time, how many gallons of ice cream can 3 ice cream machines make?
If two ice cream machines make 320 gallons of ice cream in a certain amount of time, then each machine makes 320/2 = <<320/2=160>>160 gallons of ice cream.
Working for the same length of time, 3 ice cream machines make a total of 160*3 = <<160*3=480>>480 gallons of ice cream. Answer: \boxed{480}.