The ratio between the present ages of A and B is 3 : 5 respectively. If the difference between B's present age and A's after 7 year is 3 what is the total of A's and B's present age ?

At present the ratio between the ages of Rahul and Nirdosh is 2 : 1 after 7 years, Rahul's age will be 21 years. what is the age of Nirdosh at present ?

Present age of A and B are in the ratio of 6 : 7 respectively. 8 years hence, the ratio of ages will become 7 : 8 respectively. What is A's present age in years ?