Tom had £10, Bob had £10 and Mark had £10.
So they clubed together and brought it for £30.
After leaving the store, the shopkeeper thought - that ReVoMaze was in the sale for £25. So taking 5 x £1 coins from the till, he ran after them.
Just before he reached them, he decided to pocket £2 and give them £1 each back.
Here is the thing: Tom, Bob and Mark paid £10 and got £1 back making £9 paid. So each of them paid £9 making £27. The shopkeeper kept £2
Who had the other £1?

