Let, the time when Jan cough up to Carol = x
We know, Distance = Speed * Time.
So, Equation would be: 2x + 5*2 = 6x
2x + 10 = 6x
6x - 2x = 10
4x = 10
x = 10/4 = 2.5
Distance traveled in that time = 2.5 * 6 = 15 miles
In short, Your Answer would be: 15 miles
Hope this helps!