The ratio of the present age of Chinky and Minky is 4 ∶ 5 and the present age of Chinky’s mother is 9/2 times Minky’s age 5 years ago and the present age of Minky’s mother is 7/3 times of Chinky’s age after 3 years. If after 15 years the average age of Minky’s mother and Chinky’s mother is 55, then find the Difference between Chinky’s and Minky’s present age.