Unbeknown Paedobaptist

Here is a post where I require your cooperation. This is one of many puzzles I can give you from a little book that my Auntie gave me a while back. Unfortunately, they aren't that good. I need you to post me your suggested answers to this mind bending puzzles. I would encourage you to guess and not just Jon and Rich offer suggestions. You don't have to put your name if you are too embarrassed but just guess. It will be fun. You never know, you might guess correctly (that is if you are clever enough)
So here is an easy enough one to start off with...
Two Fathers and two Sons enter a shop and spend £1.50 each. The shopkeeper takes £4.50. What happened to the rest?
So come on, be daring, be the man (or woman, whatever takes your fancy)....