Can some one explain to me how to get 2.6 bar notation from 2 2/3

Fanny mendelssohn manages all the magazines and paperback books at a local grocery store. she prices many paperbacks to sell at $7.99. the cost to the store is $5.29. what is the markup rate on a paperback book, based on its cost?

Bob is putting books on a shelf and takes a break after filling 18 1/2 inches on the book shelf. the book shelf is now 2/3 full. how long is the entire bookshelf?

Atotal of 766 tickets were sold for the school play. they were either adult tickets or student tickets. there were 66 more student tickets sold than adult tickets. how many adult tickets were sold?