Could someone please help me with this answer thank you!

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.

Idon’t understand! use slope intercept form to solve: through: (2,5) slope= undefined

Could someone with number 1 and 2