I assumed that North was the beginning of the first angle (A), so I drew a 125 deg angle from there and marked the length as 40 km. Then from that point, I sketched N again and drew a 210 deg angle at a length of 100 km. Then I drew the line from the end of the 100 km to A. Then I determined the angles inside the triangle by subtracting 210 deg from 360 deg, and 125 deg from 180 deg and subtracting that from the 360-210. Then adding those 2 results and subtracting from 180 deg for the bottom angle of the triangle. Then I used the law of cosines to determine the distance asked for. x^2 =(40^2) + (100^2) - [2(40)(100)* cos 115 deg]. I got x = 122.40 km Note: If you need a drawing, I will try to figure out how to do that here, never done it so far.
spoiler: If top angle of triangle is B, right-side angle C and bottom angle is A, then Angle A is 10 deg, angle B is 55 deg, and angle C is 115 deg.