Edmund's Brainteasers
Problem 5
Problem 5: Books at the jumble sales
The Church holds 4 jumble sales each year. Those in December, March and May are held in the Church Hall and one in September is held in the Town Hall. Books are sold on a remarkably regular basis. At every sale in the Church Hall 30 books are sold and at every sale in the Town Hall 60 books are sold. Donations of books are also remarkably regular with exactly 45 books being donated between two sales. At the start of the September 2005 sale, 260 books were on sale. Of course books left over at the end of one sale are carried forward to the next. Which is the first sale to have over 300 books left at the end.