Any angle of measure 180° or less is supplementary to some angle. A supplementary angle is one that is the difference between 180° and the angle you have. That is, two supplementary angles total 180°.
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Supplementary angles are readily identifiable in a number of geometries. Adjacent angles of a parallelogram are supplementary; linear angles are supplementary. Same-side interior angles where a transversal crosses parallel lines are supplementary.
<span>Since one standard deviation is 20 luggages, 3 standard deviations above the mean is 3*20=60 luggages above the mean of 380 luggages, so 60+380 gives the answer C, 440.</span>
