Her hair is 6 feet long. There are 12 inches in a foot. Each ponytail is 6 inches to donate. This means that there are 2 ponytails in each foot. Since she has 6 feet of hair, you multiply 6 by 2 because there are two ponytails to a foot of hair. The answer is 12 ponytails.
I hope this helps! Please let me know if you have any questions.