The present age of father and son are in the ratio 3: 1. After 20 years the ratio becomes 2 : 1 . Find the present age of the father. 

Two years ago, the ratio of the age (in years) at A and B was 2:3. The ratio of their respective ages, three years from now, will be 3:5. What will be the ratio of respective ages of A and B, 6 years from now?

Present age of Ram and Shyam are in the ratio of 4: 5 respectively. Five year hence the ratio of their age becomes 5:6 respectively. What is Ram’s present age?

The multiplication of the age of Rajeev, before 5 years and after 9 years, is 15. What is the present age of Rajeev?

The ratio of present ages of Shankar and Mohan is 7: 8 respectively. Four year hence this ratio becomes 9: 10 respectively. What is Shankar’s present age in years?

Sum of A’s and B’s age 6 years ago is 88. A’s age 18 yrs ago is equal to B’s age 6 years ago. Find the age of A two year hence?

The ratio of present ages of Ratna and Shantanu is 5:4. After 19 years, the ratio of their ages will be 10:9. What is Ratna's present age?

The average weight of 15 students of a class increases by 1.5 kg when a student of 40 kg is replaced by a new student. What is the weight (in kg) of the new student?