The hotel bill for a number of people for overnight stay is ₹4800 . If there were 4 more the bill each person had to pay would have reduced by ₹200. Find the number of people staying overnight.

A person was given ₹3000 for a tour. If he extends his tour programme by 5 days, he must cut down his daily expense by ₹20. Find the number of days of his tour programme.

The sum of the ages of Vivek and his youger brother Amit is 47 years. The product of their ages in years is 550. Find their ages.

Paul is x years old and his father's age is twice the square of Paul's age. Ten years hence, father's age will be four times Paul's age. Find their present ages.