State whether set of ordered pairs represent a function {(-13,4) , (7,-15), (-13,9) (6,-12) (-18,0)

Mr and mrs smith buy tickets for themselves and their four children. the cost of an adult ticket is ? 6 more than the adult ticket. the total cost of the six tickets is ? 40.50 work out the cost of an adult ticket. in your working let c be the cost of the child ticket and a be the cost of the adult ticket.

Anyone know? will mark brainliest if correct

The parabola x= √y-9 opens: a.)up b.)down c.)right d.)left