The reverse bearing is different by 180°. It will be ...
Q from P = (120° +180°) = 300°
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<em>Additional comment</em>
Bearings are always in the range 0 to 360° (not including 360°). That means the reverse bearing will be the original less 180° when the original is 180° or more. It will be the original plus 180° when the original is less than 180° (as here).
So it took an hour an 15 minutes which means the distance traveled is their speed+1/4 of their speed, also any answers that have northbound going faster than 6km/h above south is not right so B and D seems to be out of the picture
