103. At 1337 ZT on July 17, in DR position LAT 30° 56.8' S, LONG 039° 36.5' W, you observe an amplitude of the Moon. The upper limb of the moon is on the visible horizon, bearing 263.0° psc. The variation is 20° W. What is the deviation?

The deviation is 3.6 E. The true bearing was calculated as 246.6 and the observed compass bearing was 263.0, resulting in a compass error of 16.4 W. Applying the formula Error = Variation + Deviation, a 20 W variation and a 16.4 W error yields a 3.6 E deviation.