Please help I don’t understand this!

What is the domain of the function f(x)=^9x

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.

The vet charges $45 for an office visit and $10 for each vaccination your dog needs. write an eaquation