Every item in the Just a Dollar store is priced at $1.00. When Mary Jo opens the store, there is $122.00 in the cash register. When she counts the money in the cash register at the end of the day, the total is $1,065.95. If the sales tax rate is 8.5%, how many items were sold that day?

please help i am really confused

After taxes, a $1 items sells for $1.085

So, the items sold account for all the extra money:

(1065.95-122.00)/1.085 = 870

That's how many items were sold.