Answer
1.6 miles
Explanation.
Am trying to interpret this question and am finding that you want to find the vertical change in elevation which you are calling S.
Hoping my interpretation is correct, this is how you solve it.
You are going to use the trigonometric ratio, tangent.
TanФ = opposite/adjacent
tan 15° = S/6
S = 6×tan15°
= 6 × 0.267949192
= 1.607695155
Answer
S = 1.6 miles