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 20 miles apart?
Let t be the amount of time it takes for the cyclists to be 20 miles apart.
The distance the first cyclist travels in t hours is 12t.
The distance the second cyclist travels in t hours is 6t.
12t + 6t = 200 - 20
18t = 180
t = <<10=10>>10. Answer: \boxed{10}.