Stumped on how to solve this one! the numbers just aren't making sense to me

Select the lengths in centimeters that would form a right triangle

Which statements regarding efg are true? check all that apply.

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?