There are three people in a family, and the father is 3 years older than the mother. Now the sum of the ages of the family is 80 years old. Ten years ago, the sum of the ages of the whole family was 51 years old. How old is the daughter this year?
一家三口人，爸爸比妈妈大3岁，现在他们一家人的年龄之和是80岁，10年前全家人的年龄之和是51岁，女儿今年多少岁．
<result>9</result>