The sum of the present ages of a father and his son is 46 years. Four years from now, the product of their ages will be 608 years.
(i) If the son’s present age is taken as x years, set up a quadratic equation in x based on the given data.
(ii) Solve the quadratic equation and hence find their present ages.
(iii) After how many years from now will the father’s age be exactly double that of his son? Show your working clearly.