Dogs in the GoodDog Obedience School win a blue ribbon for learning how to sit, a green ribbon for learning how to roll over, and a white ribbon for learning how to stay. There are 100 dogs in the school.
* 62 have blue ribbons, 65 have green ribbons, and 50 have white ribbons.
* 35 have a blue ribbon and a green ribbon; 23 have a blue ribbon and a white ribbon; 31 have a green ribbon and a white ribbon.
* 15 have all three ribbons.
Fill in the Venn diagram.
Since 15 have all three ribbons:
35-15 = 20 with a blue and green ribbon only
23-15 = 8 with a blue and white ribbon only
31-15 = 16 with a green and white ribbon only.
So then we're gonna find all the dogs who only have one ribbon.
62-15-20-8 = 19 with blue only
65-15-20-16 = 14 with green only
50-15-8-16 = 11 with white only