A family consists of five people, Tina's brother is 6 years elder to her and the ratio of age of Tina 1 year ago and Tina's grandfather's present age is 1 ∶ 4, the ratio of the present age of her mother and father is 15 ∶ 16, the ratio of her father's and grand father's age is  2 ∶ 3.Tina's mother is 20 years elder to Tina's brother. Find the average age of the family (approximate value)?