Problem solving

Question

Lauren decorated her 18 page scrapbook. She put stickers on 16 of the pages and ribbons on nine of the pages. At least how many pages have both stickers and ribbons

Answer 1

The maximum is 9....if all the pages with ribbons also have stickers.

If you put ribbons on the 2 pages with no stickers, you now have 7 ribbons left over which must go on pages WITH stickers. So 7 is the minimum that can have both.