Two friends, Alex and Bob, go to a bookshop, together with their sons Peter and Tim. All four of them buy some books. Each book costs a whole amount of shillings.

When they leave the shop, they notice that both fathers have spent 21 shillings more than their respective sons. Moreover, each of them paid per book the same amount of shillings as the number of books that he bought.

The difference between the number of books that Alex bought and that Peter bought is five.

Who is the father of Tim?

Alex is the father of Tim.

Alex bought 5 books for 5² = 25 shillings.
Tim bought 2 books for 2² = 4 shillings.
25 - 4 = 21.

Bob bought 11 books for 11² = 121 shillings.
Peter bought 10 books for 10² = 100 shillings.
121 - 100 = 21.

The difference of books Alex and Peter bought is |5 - 10| = 5.

Posted by Dej Mar on 2008-06-04 16:21:14