Two cyclists are 200 miles apart when they start racing toward each other. If their speeds are 12 mph and 6 mph, how much time will pass before they are twenty miles apart?
When the two cyclists start racing toward each other, the total speed at which they are moving towards each other is 12 + 6 = <<12+6=18>>18 mph.
To cover the remaining twenty miles, they will take 20/18 = <<20/18=1.1111111111111112>>1.11... hours.
This is equal to 1 hour and 0.11 x 60 = <<1*60+0.11*60=6.6>>6.6 minutes.
Thus, the time it will take before they are twenty miles apart is 1 hour and 6.6 minutes. Answer: \boxed{1 \text{ hour and 6.6 minutes}}.