The bearing of Y from X is 085º. What is the bearing of X from Y?

Analyze the question: The bearing of Y from X is 085°. We need the bearing of X from Y, which is the "back bearing."

Concept: Bearings are measured clockwise from North. The back bearing differs from the forward bearing by 180°.

• If the bearing is less than 180°, add 180°.
• If it is more than 180°, subtract 180°.

Solution:

• Bearing of Y from X = 085°
• Since 085° < 180°, add 180°: 085° + 180° = 265°

Check with a sketch: At X, draw a North line. Y lies 85° clockwise from North, so it is almost due East, slightly north of the east direction. From Y, X lies in the opposite direction, which is almost due West, slightly south. Due West is 270°, so slightly south of West gives a bearing a little less than 270°, which matches 265°.

Answer: The bearing of X from Y is 265°, which is option D.

Tip: For back bearings, remember "less than 180, add; more than 180, subtract." Also, the two bearings must always differ by exactly 180°. Option B (095°) is a common trap, as it only measures the angle from the wrong reference.