Can somone explain how I solve this I was absent when we went over this

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.

With both problems. a.s.a.p directions on photo ^

What multiplys to be 1 but adds up to be 4