1. Problem: Given True Course (TC) and Magnetic Variation (MV), find Magnetic Course (MC). Magnetic Variation West means subtract variation from True Course. Calculate: $$MC = TC - MV$$ For 1: $$MC = 121.5^\circ - 4^\circ = 117.5^\circ$$ 2. For 2: $$MC = 268^\circ - 2.5^\circ = 265.5^\circ$$ 3. Magnetic Variation East means add variation: $$MC = TC + MV$$ For 3: $$MC = 85^\circ + 4^\circ = 89^\circ$$ 4. Given Magnetic Course and Deviation (Deviation West means subtract deviation from MC to find True Course): $$TC = MC - Deviation$$ For 4: $$TC = 275^\circ - 2^\circ = 273^\circ$$ 5. Problem: Given True Course and relative bearing to starboard (right), find true bearing of another vessel. True Bearing = True Course + relative bearing For 5: $$True\ Bearing = 135^\circ + 20^\circ = 155^\circ$$ 6. Given True Course and true bearing of lighthouse, find relative bearing: $$Relative\ Bearing = True\ Bearing - True\ Course$$ For 6: $$Relative\ Bearing = 120^\circ - 75^\circ = 45^\circ$$ 7. Target observed 45° to port (left): relative bearing is negative: $$True\ Bearing = True\ Course - relative\ bearing$$ For 7: $$True\ Bearing = 95^\circ - 45^\circ = 50^\circ$$ 8. Vessel on true course 5° with another vessel 35° to starboard: $$True\ Bearing = 5^\circ + 35^\circ = 40^\circ$$ 9. Magnetic Course = 358°, Deviation = 3°E (East means add deviation to get Compass Course): $$Compass\ Course = MC + Deviation = 358^\circ + 3^\circ = 361^\circ = 1^\circ$$ (mod 360) 10. Magnetic Course = 50°, Deviation = 4.5°E: $$Compass\ Course = 50^\circ + 4.5^\circ = 54.5^\circ$$ 11. Magnetic Course = 100°, Deviation = 5°E: $$Compass\ Course = 100^\circ + 5^\circ = 105^\circ$$ 12. Compass Course = 215°, Deviation 3.5°W (West means subtract deviation from Compass Course to find Magnetic Course): $$Magnetic\ Course = Compass\ Course - Deviation = 215^\circ - 3.5^\circ = 211.5^\circ$$ 13. Magnetic Variation is the difference between True and Magnetic Course: $$MV = TC - MC$$ For 13: $$MV = 285^\circ - 281^\circ = 4^\circ\ W$$ (since MC < TC) 14. For 14: $$MV = 285^\circ - 285^\circ = 0^\circ$$ 15. Given Magnetic Course and Compass Course, find Deviation: Deviation = Compass Course - Magnetic Course For 15: $$Deviation = 356^\circ - 0^\circ = 356^\circ = -4^\circ$$ mod 360 which means 4°W deviation. Final answers summary: 1. 117.5° 2. 265.5° 3. 89° 4. 273° 5. 155° 6. 45° 7. 50° 8. 40° 9. 1° 10. 54.5° 11. 105° 12. 211.5° 13. 4°W 14. 0° 15. 4°W