A grade 11 class, on a field trip to Montreal, had lunch in a restaurant. The bill came to $239.25….

A grade 11 class, on a field trip to Montreal, had lunch in a restaurant. The bill came to $239.25. Four students had birthdays that day, and it was agreed that these four should not have to pay for lunch. The other students had to pay $1 more than if all the students had paid. How many students had lunch?