The average of the first 100 positive integers is

In a family, the average age of a father and a mother is 35 years. The average age of the father, mother and their only son is 27 years. What is the age of the son?

If 5 men or 7 women can earn Rs. 5,250 per day, how much would 7 men and 13 women earn per day ?

If A and B together can complete a piece of work in 15 days and B alone in 20 days, in how many days can A alone complete the work ?

By walking at 3/4 of his usual speed, a man reaches his office 20 minutes later than his usual time. The usual time taken by him to reach his office is