Puzzle - Rate
Yesterday my mother asked me to buy some stamps. Stamps, in the land of BrainBashers, are available in 3p, 9p, 11p, 17p and 21p denominations.
For three types of stamp I was asked to buy eight of each. For the other two types of stamp, I was asked to buy nine of each.
Unfortunately I forgot which I was supposed to buy eight of and which to buy nine of.
Luckily my mother had given me the exact money required to buy the stamps, £5.00 and the shopkeeper was able to give me the correct stamps.
Which stamps did I buy?
[Ref: ZNRA] © Kevin Stone