How to solve one step equations? how do i add a fraction with a whole number in one step equations?

Anne is twice as old as bill, and bill is 3 years older than christie. the sum of anne s and christie s ages equal 72. find their age difference.?

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.

At a sale this week, a desk is being sold for $213. this is a 29% discount from the original price. what is the original price?