When class 11Y1 found that their favourite teacher, Mr Musson, was leaving they decided to organise a party for him. Lewis, one of the class members, wants to buy 38 cartons of juice. He can buy a single carton of juice for 45p. He can buy a pack of 4 cartons for £1.56 Lewis buys all the cartons he needs for the least possible amount of money. How much did he spend?