A hotelier wanted to furnish the dining room with new chairs. In the catalog, he chose a type of chair. Only when placing the order did he learn from the manufacturer that as part of a discount offer, every fourth chair was offered at half price, and that he could thus save the equivalent of seven and a half chairs compared to his original plan. The hotelier calculated that with the originally planned amount, he could purchase nine more chairs than he intended.

How many chairs did the hotelier originally want to buy?

(L. Simünek)

Hint. First solve the problem without the information that with the originally planned amount, nine more chairs can be purchased.