Answer:
10
Explanation:
We cannot use the Pythagorean Theorem here because we only have one side length. However, we can use the fact that

I decided to make the corner with the 60° as ∠A, the corner with the 30° as ∠B, and the corner with the right angle as ∠C. While then making side a as the unmarked side, side b as the side with 5, and the hypotenuse p as side c.
Since we do not need to solve for a in this equation to solve for p, we can simply use the sides and numbers we are given.
Manipulating two of our equations, preferably the equations with the variables b and c, we can get
and solving for c, which is p in this case, will give us

Plugging in the numbers we have gives us
= 10 mi