Yesterday I was asked to buy some stamps.
Stamps, in the land of BrainBashers, are available in 2p, 7p, 10p, 15p and 20p denominations.
For three types of stamp, I was asked to buy five of each.
For the other two types of stamps, I was asked to buy six of each.
Unfortunately, I forgot which I was supposed to buy five of and which to buy six of.
I had been given £3.00, which just happened to be the exact money required, so the shopkeeper was able to work out what stamps I needed.
Which stamps did I buy?