Mrs.James had 12 biographies, 18 storybooks and 6 reference books in her classroom library. She arranged each type of book on shelves with 6 books on each shelf. How many shelves did Mrs james use to arrange all of her books?

Rob baby sits the kids next door everyday after school for 1.5 hours.He earns $3.50 an hour.How much money will he earned in 6 weeks if school is in session 5 days a week the whole time?