Question

If the bearing of A from B is 120⁰ what is the bearing of B from A?​

Answer 1

Check the picture below.

let's recall that the Bearing is always the angle made with the North line and is always Clockwise.

Now, by alternate interior angles, if one is 120° and they're both in the same line, the other must be 180° - 120° = 60°. Since a full circle has 360°, 360° - 60° = 300°.