Calculate the size of ?

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.

If you answer 2+2 you will get over 80 points

The sum of these consecutive integers is equal to 9 less than 4 times the least of the integer. find the three integers