This is a old puzzle, and there are different variations, but can you work it out?
Three old ladies decide to buy a television. They see a second-hand black and white set for £30.The manager feels generous, he tells the assistant to give the old ladies £5 back.
But the assistant gives each old lady only £1 and keeps £2 for himself. So the old ladies have spent £9 each, £27 in total. The assistant has £2 in his pocket.
Where has the other £1 gone?