For this case we have the following equation: Where, d: the distance they can see in thousands h: their eye-level height in feet For Kaylib: For Addison: Subtracting both distances we have: Answer: B. 2√2 mi
If x=n then it would have 2 solutions because it would be x^2 = c which has a positive and negative solution but idk if that is what you are asking for