Answer: 10 miles
If you draw what the problem is explaining, you should get a triangle. 2 of the sides should be 6 and 8.
To find the missing side, use the Pythagorean theorem to solve for the missing side.
[tex] {a}^{2} + {b}^{2} = {c}^{2} \\ {8}^{2} + {6}^{2} = 100 \\ \sqrt{100} = 10[/tex]