Why do we call a "w" w?

What function has a range {yly< 5}? question on picture above^

The serenity and the mystic are sail boats. the serenity and the mystic start at the same point and travel away from each other in opposite directions. the serenity travels at 16 mph and the mystic travels at 19 mph. how far apart will they be in 3 hours?

Astudent showed the steps below while solving the inequality |x-4|< 1 by graphing.