Answer:
2 miles
Explanation:
Perimeter is figured out by adding all 4 sides of a rectangle.
So if the width is 7 miles on 1 side, the other width side is also 7 miles.
If the perimeter was 18 miles and 14 miles of that was the width on both sides, that leaves only 4 miles left for the 2 length sides. That means each length side is 2 miles.