Which of these tables represents a function?

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?

During the election for class president, 40% of the students voted for kellen, and 60% of the students voted for robbie. 500 students voted in total. how many more students voted for robbie than for kellen? answer with work : )

Macy spent $36 on jeans. this was $12 less than twice what she spent on a shirt. which equation to solve this, 12x=36 2x=36-12 2x-12=36 12-2x=36