One of the keys here is they specify "on airway" so you have
to make sure you stay on them and take no shortcuts.
The first one SHG is not on UH42, darn close but not on it so you would
not be on airways.
The second one LAV to Cindy is not an airway, again the wording.
The third one, there is no intersection/waypoint where 12 and 872 meet.
Also, 872 has a very large arrow pointing the opposite
direction. One way street.
This is a popular Exam question ...... and the 'normal' error is the
UH42/SHG bit .... UH42 does not go through SHG