14. The purchase costs 19 rubles. The buyer has only three-ruble bills, and the cashier has only five-ruble bills. Can the purchase be paid for with the available money, and if so, how exactly? (Limit the case to when the buyer and the cashier each have 15 bills of the specified denomination).
14. 19 rubles can be paid in two ways:
1) the buyer gives 24 rubles and receives 5 rubles in change. 2) gives 39 rubles and receives 20 rubles in change.