Mr. R.’s World of Math

     Mr. Morris, the principal was very mad the students had painted their classroom with purple swirls and gray polka-dots. Mr. Morris didn’t even like polka dots, and purple was his least favorite color.
     “I’m very disappointed in you,” said Mr. Morris, “I’m sure your parents will be very upset when they hear about this.”
     “Our parents! Do you have to tell our parents?” cried Serena. Serena was one of the best students in the school and her parents were going to be very upset if they found out that she and some of her friends had painted the classroom purple.
     “Not only am I going to tell your parents,” said Mr. Morris, “but as a punishment you’re going to have to come to school for 8 hours of extra school work for the next 5 Saturdays with your teacher, Mr. R.!”

How many extra hours were the students going to have to come to school for over the next 5 Saturdays?