I have attached an image showing the triangle with angle and distance depicted in the question.
Answer:
151 miles
Step-by-step explanation:
We have to first find the unknown angle in the triangle.
Sum of angles in a triangle is 180°.
Thus, if we call angle at Norfolk A, we have;
A = 180 - (83 + 31)
A = 66°
Using sine rule, we can find the distance which we will term as a.
Thus;
a/sin 83 = 139/sin 66
a = (139 × sin 83)/sin 66
a = 137.963915/0.913545
a ≈ 151 miles