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.

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 age of a man is twice the square of the age of his son. Eight years hence, the age of the man will be 4 years more than 3 times the age of his son. Find their present ages.

Ritu bought a saree for ₹60x and sold it for ₹(500 + 4x) at a loss of x%. Find the cost price.